From a04eb12f7a47992d1e352b3126479ef9a3f28eee Mon Sep 17 00:00:00 2001 From: Mats Wichmann Date: Sun, 1 Sep 2019 13:30:53 -0600 Subject: Builder and Variable Subst doc updates [ci skip] Work on Builder Methods and Variable Substitution man sections - some wording tweaks, do some formatting markup a little more consistently, etc. Tweak the wording for the Command builder, a description shared between manpage and userguide. Closes #3030: Environment.xml had many references to detail sections elsewhere, like "see XXX section below," which don't work well - this xml is generated into both the manpage and the user guide, and the locality of saying "below" is incorrect for the latter since those sections are only in the manpage. Essentially these are changed to say "see the manpage section XXX". Adding clickable links is of course also possible, but I recall there was some objection to cross-document links, so I didn't do that. Signed-off-by: Mats Wichmann --- doc/man/scons.xml | 362 +++++++++++++++++++++++---------------- src/engine/SCons/Environment.xml | 96 ++++++----- 2 files changed, 267 insertions(+), 191 deletions(-) diff --git a/doc/man/scons.xml b/doc/man/scons.xml index faec455..c1773c7 100644 --- a/doc/man/scons.xml +++ b/doc/man/scons.xml @@ -1921,7 +1921,7 @@ These warnings are enabled by default. feature not working when scons -is run with the python +is run with the Python option or from optimized Python (.pyo) modules. @@ -2048,7 +2048,7 @@ env['BAR'] = 'bar' As a convenience, construction variables may also be set or modified by the -parse_flags +parse_flags keyword argument, which applies the &f-link-env-MergeFlags; method (described below) to the argument value @@ -2228,7 +2228,7 @@ def exists(env): return True # in SConstruct: -env = Environment(tools = ['default', ('my_tool', {'arg1': 'abc'})], +env = Environment(tools=['default', ('my_tool', {'arg1': 'abc'})], toolpath=['tools']) @@ -2247,7 +2247,7 @@ With a nested tool name the dot represents a directory seperator # namespaced builder -env = Environment(ENV = os.environ, tools = ['SubDir1.SubDir2.SomeTool']) +env = Environment(ENV=os.environ, tools=['SubDir1.SubDir2.SomeTool']) env.SomeTool(targets, sources) # Search Paths @@ -2293,75 +2293,104 @@ env.SomeTool(targets, sources) Builder Methods -Build rules are specified by calling a construction -environment's builder methods. -The arguments to the builder methods are -target -(a list of targets to be built, -usually file names) +You tell scons what to build +by calling Builders, functions which know to take a +particular action when given files of a particular type +to produce a particular result type. scons +defines a number of builders, and you can also write your own. +Builders are attached to a &consenv; as methods, +and the available builder methods are listed as +key-value pairs in the +BUILDERS attribute of the &consenv;. +The available builders can be displayed like this +for debugging purposes: + + + +print("Builders:", list(env['BUILDERS'])) + + + +Builder methods always take two arguments: +target +(a target or a list of targets to be built) and -source -(a list of sources to be built, -usually file names). +source +(a source or list of sources to be used as input +when building), +although in some circumstances, +the target argument can actually be omitted (see below). +Builder methods also take a variety of +keyword arguments, described below. + Because long lists of file names can lead to a lot of quoting, scons -supplies a -Split() +supplies a &Split; global function and a same-named environment method that split a single string into a list, separated on strings of white-space characters. -(These are similar to the split() member function of Python strings -but work even if the input isn't a string.) +(These are similar to the Python string split +method, but work even if the input isn't a string.) -Like all Python arguments, -the target and source arguments to a builder method -can be specified either with or without -the "target" and "source" keywords. -When the keywords are omitted, -the target is first, -followed by the source. -The following are equivalent examples of calling the Program builder method: + +The target and source arguments to a builder method +can be specified either as positional arguments, +in which case the target comes first, or as +keyword arguments, using target= +and source=. +The following are equivalent examples of calling the +&Program; builder method: + env.Program('bar', ['bar.c', 'foo.c']) env.Program('bar', Split('bar.c foo.c')) env.Program('bar', env.Split('bar.c foo.c')) -env.Program(source = ['bar.c', 'foo.c'], target = 'bar') -env.Program(target = 'bar', Split('bar.c foo.c')) -env.Program(target = 'bar', env.Split('bar.c foo.c')) -env.Program('bar', source = 'bar.c foo.c'.split()) +env.Program(source=['bar.c', 'foo.c'], target='bar') +env.Program(target='bar', source=Split('bar.c foo.c')) +env.Program(target='bar', source=env.Split('bar.c foo.c')) +env.Program('bar', source='bar.c foo.c'.split()) -Target and source file names -that are not absolute path names -(that is, do not begin with -/ -on POSIX systems -or -\ -on Windows systems, -with or without -an optional drive letter) -are interpreted relative to the directory containing the -SConscript -file being read. -An initial -# -(hash mark) -on a path name means that the rest of the file name -is interpreted relative to -the directory containing -the top-level -SConstruct -file, -even if the -# -is followed by a directory separator character -(slash or backslash). + +Python follows the POSIX pathname convention for path +strings: if a string begins with the operating system pathname separator +(on Windows both the slash and backslash separator work, +and any leading drive specifier is ignored for +the determination) it is considered an absolute path, +otherwise it is a relative path. +If the path string contains no separator characters, +it is searched for as a file in the current directory. If it +contains separator characters, the search follows down +from the starting point, which is the top of the directory tree for +an absolute path and the current directory for a relative path. + + +scons recognizes a third way to specify +path strings: if the string begins with +the # character it is +top-relative - it works like a relative path but the +search follows down from the directory containing the top-level +SConstruct rather than +from the current directory (the # is allowed +to be followed by a pathname separator, which is ignored if +found in that position). +Top-relative paths only work in places where &scons; will +interpret the path (see some examples below). To be +used in other contexts the string will need to be converted +to a relative or absolute path first. + + + +Target and source pathnames can be absolute, relative, or +top-relative. Relative pathnames are searched considering the +directory of the SConscript +file currently being processed as the "current directory". + Examples: @@ -2403,12 +2432,12 @@ executable program or bar.exe (on Windows systems) -from the bar.c source file: +from the bar.c source file: -env.Program(target = 'bar', source = 'bar.c') -env.Program('bar', source = 'bar.c') -env.Program(source = 'bar.c') +env.Program(target='bar', source='bar.c') +env.Program('bar', source='bar.c') +env.Program(source='bar.c') env.Program('bar.c') @@ -2418,28 +2447,31 @@ keyword argument may be specified when calling a Builder. When specified, all source file strings that are not absolute paths +or top-relative paths will be interpreted relative to the specified srcdir. The following example will build the -build/prog +build/prog (or -build/prog.exe +build/prog.exe on Windows) program from the files -src/f1.c +src/f1.c and -src/f2.c: +src/f2.c: + env.Program('build/prog', ['f1.c', 'f2.c'], srcdir='src') -It is possible to override or add construction variables when calling a -builder method by passing additional keyword arguments. -These overridden or added -variables will only be in effect when building the target, so they will not -affect other parts of the build. For example, if you want to add additional -libraries for just one program: +It is possible to override (replace or add) +construction variables when calling a +builder method by passing them as keyword arguments. +These overrides +will only be in effect when building that target, and will not +affect other parts of the build. For example, if you want to specify +some libraries needed by just one program: env.Program('hello', 'hello.c', LIBS=['gl', 'glut']) @@ -2459,7 +2491,7 @@ for dependencies on the non-standard library names; see the descriptions of these variables, below, for more information.) It is also possible to use the -parse_flags +parse_flags keyword argument in an override, to merge command-line style arguments into the appropriate construction variables @@ -2504,8 +2536,7 @@ from SCons.Script import * All builder methods return a list-like object -containing Nodes that -represent the target or targets that will be built. +containing Nodes that will be built. A Node is an internal SCons object @@ -2517,9 +2548,8 @@ can be passed to other builder methods as source(s) or passed to any SCons function or method where a filename would normally be accepted. For example, if it were necessary -to add a specific - -flag when compiling one specific object file: +to add a specific preprocessor define +when compiling one specific object file: bar_obj_list = env.StaticObject('bar.c', CPPDEFINES='-DBAR') @@ -2530,14 +2560,14 @@ env.Program(source = ['foo.c', bar_obj_list, 'main.c']) makes for a more portable build by avoiding having to specify a platform-specific object suffix -when calling the Program() builder method. +when calling the &Program; builder method. -Note that Builder calls will automatically "flatten" +Note that builder calls will automatically "flatten" the source and target file lists, -so it's all right to have the bar_obj list -return by the StaticObject() call +so it's all right to have the bar_obj_list +returned by the &StaticObject; call in the middle of the source file list. -If you need to manipulate a list of lists returned by Builders +If you need to manipulate a list of lists returned by builders directly using Python, you can either build the list by hand: @@ -2549,8 +2579,7 @@ for object in objects: print(str(object)) -Or you can use the -Flatten() +Or you can use the &Flatten; function supplied by scons to create a list containing just the Nodes, which may be more convenient: @@ -2563,23 +2592,23 @@ for object in objects: print(str(object)) -Note also that because Builder calls return +Note also that because builder calls return a list-like object, not an actual Python list, you should not -use the Python -+= -operator to append Builder results to a Python list. +use the Python add +operator (+ or +=) +to append builder results to a Python list. Because the list and the object are different types, Python will not update the original list in place, but will instead create a new Node-list object containing the concatenation of the list -elements and the Builder results. +elements and the builder results. This will cause problems for any other Python variables in your SCons configuration that still hold on to a reference to the original list. -Instead, use the Python -.extend() +Instead, use the Python list +extend method to make sure the list is updated in-place. Example: @@ -2592,7 +2621,7 @@ object_files = [] # # It will not update the object_files list in place. # -# Instead, use the .extend() method: +# Instead, use the list extend method: object_files.extend(Object('bar.c')) @@ -2609,7 +2638,7 @@ print("The path to bar_obj is:", str(bar_obj_list[0])) Note again that because the Builder call returns a list, we have to access the first element in the list -(bar_obj_list[0]) +((bar_obj_list[0])) to get at the Node that actually represents the object file. @@ -2672,7 +2701,12 @@ to use just the filename portion of the targets and source. scons -provides the following builder methods: +predefined the following builder methods. +Depending on the setup of a particular +&consenv; and on the type and software +installation status of the underlying system, +not all builders may be available to that +&consenv;. @@ -4409,7 +4443,7 @@ functions return and Dir Nodes, respectively. -python objects, respectively. +Python objects, respectively. Those objects have several user-visible attributes and methods that are often useful: @@ -5426,17 +5460,15 @@ a = Action(build_it, varlist=['XXX']) The -Action() +&Action; global function can be passed the following optional keyword arguments to modify the Action object's behavior: - -chdir -The -chdir -keyword argument specifies that + +chdir +specifies that scons will execute the action after changing to the specified directory. If the @@ -5481,15 +5513,9 @@ a = Action("build < ${SOURCE.file} > ${TARGET.file}", chdir=1) - -exitstatfunc -The -Action() -global function -also takes an -exitstatfunc -keyword argument -which specifies a function + +exitstatfunc +specifies a function that is passed the exit status (or return value) from the specified action @@ -5511,11 +5537,9 @@ a = Action("build < ${SOURCE.file} > ${TARGET.file}", -batch_key -The -batch_key -keyword argument can be used -to specify that the Action can create multiple target files + +batch_key +specifies that the Action can create multiple target files by processing multiple independent source files simultaneously. (The canonical example is "batch compilation" of multiple object files @@ -5524,7 +5548,7 @@ to a single invocation of a compiler such as Microsoft's Visual C / C++ compiler.) If the batch_key -argument is any non-False, non-callable Python value, +argument evaluates True and is not a callable object, the configured Action object will cause scons to collect all targets built with the Action object @@ -5556,7 +5580,7 @@ will be used to identify different for batch building. A batch_key -function must take the following arguments: +function must accept the following arguments: @@ -5688,7 +5712,7 @@ sequences of file manipulation without relying on platform-specific external commands: -that + env = Environment(TMPBUILD = '/tmp/builddir') env.Command('foo.out', 'foo.in', @@ -5848,13 +5872,13 @@ env.Command('marker', 'input_file', Before executing a command, scons -performs construction variable interpolation on the strings that make up -the command line of builders. -Variables are introduced by a -$ +performs construction variable interpolation on the string that makes up +the command line of the builder. +Variables are introduced in such strings by a +$ prefix. -Besides construction variables, scons provides the following -variables for each command execution: +Besides regular construction variables, scons provides the following +special variables for each command execution: @@ -5923,15 +5947,19 @@ from sources that have not changed since the target was last built. -(Note that the above variables are reserved -and may not be set in a construction environment.) - -For example, given the construction variable CC='cc', targets=['foo'], and -sources=['foo.c', 'bar.c']: +Note that the above variables are reserved +and may not be set in a construction environment. + +For example, given the construction variables +CC='cc', +targets=['foo'] +and +sources=['foo.c', 'bar.c']: + action='$CC -c -o $TARGET $SOURCES' @@ -5944,7 +5972,8 @@ cc -c -o foo foo.c bar.c Variable names may be surrounded by curly braces ({}) -to separate the name from the trailing characters. +to separate the name from surrounding characters which +are not part of the name. Within the curly braces, a variable name may have a Python slice subscript appended to select one or more items from a list. @@ -6107,20 +6136,42 @@ may be a callable Python function associated with a construction variable in the environment. The function should -take four arguments: -target -- a list of target nodes, -source -- a list of source nodes, -env -- the construction environment, -for_signature -- a Boolean value that specifies +accept four arguments: + + + + target + +a list of target nodes + + + + source + +a list of source nodes + + + + env + +the construction environment + + + + for_signature + +a Boolean value that specifies whether the function is being called -for generating a build signature. +for generating a build signature. + + + + + SCons will insert whatever the called function returns -into the expanded string: +into the expanded string: + def foo(target, source, env, for_signature): @@ -6201,9 +6252,10 @@ echo Last build occurred . > $TARGET Python Code Substitution -Any python code within -${-} -pairs gets evaluated by python 'eval', with the python globals set to +Any Python code within +curly braces (and introduced by the variable prefix $) +gets evaluated by the Python eval statement, +with the Python globals set to the current environment's set of construction variables. So in the following case: @@ -6219,14 +6271,20 @@ echo FOO > foo.out echo BAR > foo.out -according to the current value of env['COND'] when the command is -executed. The evaluation occurs when the target is being -built, not when the SConscript is being read. So if env['COND'] is changed +according to the current value of env['COND'] +when the command is executed. +The evaluation takes place when the target is being +built, not when the SConscript is being read. So if +env['COND'] is changed later in the SConscript, the final value will be used. -Here's a more interesting example. Note that all of COND, FOO, and -BAR are environment variables, and their values are substituted into -the final command. FOO is a list, so its elements are interpolated +Here's a more interesting example. Note that all of +COND, +FOO, +and +BAR are construction variables, +and their values are substituted into the final command. +FOO is a list, so its elements are interpolated separated by spaces. @@ -6574,9 +6632,10 @@ do this, in part, by sharing an ability to interpret UNIX-like path names. For example, the Cygwin tools will internally translate a Cygwin path name -like /cygdrive/c/mydir +like /cygdrive/c/mydir to an equivalent Windows pathname -of C:/mydir (equivalent to C:\mydir). +of C:/mydir (equivalent to C:\mydir). + Versions of Python that are built for native Windows execution, @@ -6584,7 +6643,8 @@ such as the python.org and ActiveState versions, do not have the Cygwin path name semantics. This means that using a native Windows version of Python to build compiled programs using Cygwin tools -(such as gcc, bison, and flex) +(such as gcc, bison, +and flex) may yield unpredictable results. "Mixing and matching" in this way can be made to work, diff --git a/src/engine/SCons/Environment.xml b/src/engine/SCons/Environment.xml index f222620..a635108 100644 --- a/src/engine/SCons/Environment.xml +++ b/src/engine/SCons/Environment.xml @@ -148,9 +148,9 @@ appending to this list, although the more flexible approach is to associate scanners with a specific Builder. -See the sections "Builder Objects" -and "Scanner Objects," -below, for more information. +See the manpage sections "Builder Objects" +and "Scanner Objects" +for more information. @@ -160,7 +160,8 @@ below, for more information. A reserved variable name that may not be set or used in a construction environment. -(See "Variable Substitution," below.) +(See the manpage section "Variable Substitution" +for more information). @@ -170,7 +171,8 @@ that may not be set or used in a construction environment. A reserved variable name that may not be set or used in a construction environment. -(See "Variable Substitution," below.) +(See the manpage section "Variable Substitution" +for more information). @@ -180,7 +182,8 @@ that may not be set or used in a construction environment. A reserved variable name that may not be set or used in a construction environment. -(See "Variable Substitution," below.) +(See the manpage section "Variable Substitution" +for more information). @@ -190,7 +193,8 @@ that may not be set or used in a construction environment. A reserved variable name that may not be set or used in a construction environment. -(See "Variable Substitution," below.) +(See the manpage section "Variable Substitution" +for more information). @@ -200,7 +204,8 @@ that may not be set or used in a construction environment. A reserved variable name that may not be set or used in a construction environment. -(See "Variable Substitution," below.) +(See the manpage section "Variable Substitution" +for more information). @@ -210,7 +215,8 @@ that may not be set or used in a construction environment. A reserved variable name that may not be set or used in a construction environment. -(See "Variable Substitution," below.) +(See the manpage section "Variable Substitution" +for more information). @@ -220,7 +226,8 @@ that may not be set or used in a construction environment. A reserved variable name that may not be set or used in a construction environment. -(See "Variable Substitution," below.) +(See the manpage section "Variable Substitution" +for more information). @@ -230,7 +237,8 @@ that may not be set or used in a construction environment. A reserved variable name that may not be set or used in a construction environment. -(See "Variable Substitution," below.) +(See the manpage section "Variable Substitution" +for more information). @@ -255,8 +263,8 @@ that are part of this construction environment. Creates an Action object for the specified action. -See the section "Action Objects," -below, for a complete explanation of the arguments and behavior. +See the manpage section "Action Objects" +for a complete explanation of the arguments and behavior. @@ -359,7 +367,8 @@ has been built. The specified action(s) may be an Action object, or anything that can be converted into an Action object -(see below). +See the manpage section "Action Objects" +for a complete explanation. @@ -386,7 +395,8 @@ is built. The specified action(s) may be an Action object, or anything that can be converted into an Action object -(see below). +See the manpage section "Action Objects" +for a complete explanation. @@ -512,7 +522,7 @@ Otherwise, the construction variable and the value of the keyword argument are both coerced to lists, and the lists are added together. -(See also the Prepend method, below.) +(See also the &Prepend; method). @@ -634,8 +644,8 @@ or Creates a Builder object for the specified action. -See the section "Builder Objects," -below, for a complete explanation of the arguments and behavior. +See the manpage section "Builder Objects" +for a complete explanation of the arguments and behavior. @@ -898,11 +908,15 @@ wx_env = env.Clone(parse_flags='!wx-config --cflags --cxxflags') -The &b-Command; "Builder" is actually implemented -as a function that looks like a Builder, -but actually takes an additional argument of the action -from which the Builder should be made. -See the &f-link-Command; function description +The &b-Command; "Builder" is actually +a function that looks like a Builder, +but takes a required third argument, which is the +action to take to construct the target +from the source, used for "one-off" builds +where a full builder is not needed. +Thus it does not follow the builder +calling rules described at the start of this section. +See instead the &f-link-Command; function description for the calling syntax and details. @@ -947,7 +961,7 @@ same-named existing construction variables. An action can be an external command, specified as a string, or a callable Python object; -see "Action Objects," below, +see the manpage section "Action Objects" for more complete information. Also note that a string specifying an external command may be preceded by an @@ -971,7 +985,7 @@ env.Command('foo.out', 'foo.in', env.Command('bar.out', 'bar.in', ["rm -f $TARGET", "$BAR_BUILD < $SOURCES > $TARGET"], - ENV = {'PATH' : '/usr/local/bin/'}) + ENV={'PATH': '/usr/local/bin/'}) def rename(env, target, source): import os @@ -979,7 +993,7 @@ def rename(env, target, source): env.Command('baz.out', 'baz.in', ["$BAZ_BUILD < $SOURCES > .tmp", - rename ]) + rename]) @@ -988,14 +1002,14 @@ Note that the function will usually assume, by default, that the specified targets and/or sources are Files, if no other part of the configuration -identifies what type of entry it is. +identifies what type of entries they are. If necessary, you can explicitly specify that targets or source nodes should -be treated as directoriese +be treated as directories by using the &f-link-Dir; or -env.Dir() +env.Dir functions. @@ -1011,9 +1025,9 @@ env.Command(env.Dir('$DISTDIR')), None, make_distdir) -(Also note that SCons will usually +Also note that SCons will usually automatically create any directory necessary to hold a target file, -so you normally don't need to create directories by hand.) +so you normally don't need to create directories by hand. @@ -1029,8 +1043,8 @@ so you normally don't need to create directories by hand.) Creates a Configure object for integrated functionality similar to GNU autoconf. -See the section "Configure Contexts," -below, for a complete explanation of the arguments and behavior. +See the manpage section "Configure Contexts" +for a complete explanation of the arguments and behavior. @@ -1375,7 +1389,8 @@ would supply a string as a directory name to a Builder method or function. Directory Nodes have attributes and methods that are useful in many situations; -see "File and Directory Nodes," below. +see manpage section "File and Directory Nodes" +for more information. @@ -1458,8 +1473,8 @@ Executes an Action object. The specified action may be an Action object -(see the section "Action Objects," -below, for a complete explanation of the arguments and behavior), +(see manpage section "Action Objects" +for a complete explanation of the arguments and behavior), or it may be a command-line string, list of commands, or executable Python function, @@ -1532,7 +1547,8 @@ would supply a string as a file name to a Builder method or function. File Nodes have attributes and methods that are useful in many situations; -see "File and Directory Nodes," below. +see manpage section "File and Directory Nodes" +for more information. @@ -2190,7 +2206,7 @@ and the construction variables they affect are as specified for the &f-link-env-ParseFlags; method (which this method calls). -See that method's description, below, +See that method's description for a table of options and construction variables. @@ -2658,8 +2674,8 @@ env.Requires('foo', 'file-that-must-be-built-before-foo') Creates a Scanner object for the specified function. -See the section "Scanner Objects," -below, for a complete explanation of the arguments and behavior. +See manpage section "Scanner Objects" +for a complete explanation of the arguments and behavior. -- cgit v0.12