diff options
Diffstat (limited to 'doc/Method.3')
| -rw-r--r-- | doc/Method.3 | 249 |
1 files changed, 249 insertions, 0 deletions
diff --git a/doc/Method.3 b/doc/Method.3 new file mode 100644 index 0000000..550b64a --- /dev/null +++ b/doc/Method.3 @@ -0,0 +1,249 @@ +'\" +'\" Copyright (c) 2007 Donal K. Fellows +'\" +'\" See the file "license.terms" for information on usage and redistribution +'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. +'\" +.TH Tcl_Method 3 0.1 TclOO "TclOO Library Functions" +.so man.macros +.BS +'\" Note: do not modify the .SH NAME line immediately below! +.SH NAME +Tcl_ClassSetConstructor, Tcl_ClassSetDestructor, Tcl_MethodDeclarerClass, Tcl_MethodDeclarerObject, Tcl_MethodIsPublic, Tcl_MethodIsType, Tcl_MethodName, Tcl_NewInstanceMethod, Tcl_NewMethod, Tcl_ObjectContextInvokeNext, Tcl_ObjectContextIsFiltering, Tcl_ObjectContextMethod, Tcl_ObjectContextObject, Tcl_ObjectContextSkippedArgs \- manipulate methods and method-call contexts +.SH SYNOPSIS +.nf +\fB#include <tclOO.h>\fR +.sp +Tcl_Method +\fBTcl_NewMethod\fR(\fIinterp, class, nameObj, isPublic, + methodTypePtr, clientData\fR) +.sp +Tcl_Method +\fBTcl_NewInstanceMethod\fR(\fIinterp, object, nameObj, isPublic, + methodTypePtr, clientData\fR) +.sp +\fBTcl_ClassSetConstructor\fR(\fIinterp, class, method\fR) +.sp +\fBTcl_ClassSetDestructor\fR(\fIinterp, class, method\fR) +.sp +Tcl_Class +\fBTcl_MethodDeclarerClass\fR(\fImethod\fR) +.sp +Tcl_Object +\fBTcl_MethodDeclarerObject\fR(\fImethod\fR) +.sp +Tcl_Obj * +\fBTcl_MethodName\fR(\fImethod\fR) +.sp +int +\fBTcl_MethodIsPublic\fR(\fImethod\fR) +.sp +int +\fBTcl_MethodIsType\fR(\fImethod, methodTypePtr, clientDataPtr\fR) +.sp +int +\fBTcl_ObjectContextInvokeNext\fR(\fIinterp, context, objc, objv, skip\fR) +.sp +int +\fBTcl_ObjectContextIsFiltering\fR(\fIcontext\fR) +.sp +Tcl_Method +\fBTcl_ObjectContextMethod\fR(\fIcontext\fR) +.sp +Tcl_Object +\fBTcl_ObjectContextObject\fR(\fIcontext\fR) +.sp +int +\fBTcl_ObjectContextSkippedArgs\fR(\fIcontext\fR) +.SH ARGUMENTS +.AS ClientData clientData in +.AP Tcl_Interp *interp in/out +The interpreter holding the object or class to create or update a method in. +.AP Tcl_Object object in +The object to create the method in. +.AP Tcl_Class class in +The class to create the method in. +.AP Tcl_Obj *nameObj in +The name of the method to create. Should not be NULL unless creating +constructors or destructors. +.AP int isPublic in +A boolean flag saying whether the method is to be exported. +.AP Tcl_MethodType *methodTypePtr in +A description of the type of the method to create, or the type of method to +compare against. +.AP ClientData clientData in +A piece of data that is passed to the implementation of the method without +interpretation. +.AP ClientData *clientDataPtr out +A pointer to a variable in which to write the \fIclientData\fR value supplied +when the method was created. If NULL, the \fIclientData\fR value will not be +retrieved. +.AP Tcl_Method method in +A reference to a method to query. +.AP Tcl_ObjectContext context in +A reference to a method-call context. Note that client code \fImust not\fR +retain a reference to a context. +.AP int objc in +The number of arguments to pass to the method implementation. +.AP "Tcl_Obj *const" *objv in +An array of arguments to pass to the method implementation. +.AP int skip in +The number of arguments passed to the method implementation that do not +represent "real" arguments. +.BE +.SH DESCRIPTION +.PP +A method is an operation carried out on an object that is associated with the +object. Every method must be attached to either an object or a class; methods +attached to a class are associated with all instances (direct and indirect) of +that class. +.PP +Given a method, the entity that declared it can be found using +\fBTcl_MethodDeclarerClass\fR which returns the class that the method is +attached to (or NULL if the method is not attached to any class) and +\fBTcl_MethodDeclarerObject\fR which returns the object that the method is +attached to (or NULL if the method is not attached to an object). The name of +the method can be retrieved with \fBTcl_MethodName\fR and whether the method +is exported is retrieved with \fBTcl_MethodIsPublic\fR. The type of the method +can also be introspected upon to a limited degree; the function +\fBTcl_MethodIsType\fR returns whether a method is of a particular type, +assigning the per-method \fIclientData\fR to the variable pointed to by +\fIclientDataPtr\fR if (that is non-NULL) if the type is matched. +.SS "METHOD CREATION" +.PP +Methods are created by \fBTcl_NewMethod\fR and \fBTcl_NewInstanceMethod\fR, +which +create a method attached to a class or an object respectively. In both cases, +the \fInameObj\fR argument gives the name of the method to create, the +\fIisPublic\fR argument states whether the method should be exported +initially, the \fImethodTypePtr\fR argument describes the implementation of +the method (see the \fBMETHOD TYPES\fR section below) and the \fIclientData\fR +argument gives some implementation-specific data that is passed on to the +implementation of the method when it is called. +.PP +When the \fInameObj\fR argument to \fBTcl_NewMethod\fR is NULL, an +unnamed method is created, which is used for constructors and destructors. +Constructors should be installed into their class using the +\fBTcl_ClassSetConstructor\fR function, and destructors (which must not +require any arguments) should be installed into their class using the +\fBTcl_ClassSetDestructor\fR function. Unnamed methods should not be used for +any other purpose, and named methods should not be used as either constructors +or destructors. Also note that a NULL \fImethodTypePtr\fR is used to provide +internal signaling, and should not be used in client code. +.SS "METHOD CALL CONTEXTS" +.PP +When a method is called, a method-call context reference is passed in as one +of the arguments to the implementation function. This context can be inspected +to provide information about the caller, but should not be retained beyond the +moment when the method call terminates. +.PP +The method that is being called can be retrieved from the context by using +\fBTcl_ObjectContextMethod\fR, and the object that caused the method to be +invoked can be retrieved with \fBTcl_ObjectContextObject\fR. The number of +arguments that are to be skipped (e.g. the object name and method name in a +normal method call) is read with \fBTcl_ObjectContextSkippedArgs\fR, and the +context can also report whether it is working as a filter for another method +through \fBTcl_ObjectContextIsFiltering\fR. +.PP +During the execution of a method, the method implementation may choose to +invoke the stages of the method call chain that come after the current method +implementation. This (the core of the \fBnext\fR command) is done using +\fBTcl_ObjectContextInvokeNext\fR. Note that this function does not manipulate +the call-frame stack, unlike the \fBnext\fR command; if the method +implementation has pushed one or more extra frames on the stack as part of its +implementation, it is also responsible for temporarily popping those frames +from the stack while the \fBTcl_ObjectContextInvokeNext\fR function is +executing. Note also that the method-call context is \fInever\fR deleted +during the execution of this function. +.SH "METHOD TYPES" +.PP +The types of methods are described by a pointer to a Tcl_MethodType structure, +which is defined as: +.PP +.CS +typedef struct { + int \fIversion\fR; + const char *\fIname\fR; + Tcl_MethodCallProc *\fIcallProc\fR; + Tcl_MethodDeleteProc *\fIdeleteProc\fR; + Tcl_CloneProc *\fIcloneProc\fR; +} \fBTcl_MethodType\fR; +.CE +.PP +The \fIversion\fR field allows for future expansion of the structure, and +should always be declared equal to TCL_OO_METHOD_VERSION_CURRENT. The +\fIname\fR field provides a human-readable name for the type, and is the value +that is exposed via the \fBinfo class methodtype\fR and +\fBinfo object methodtype\fR Tcl commands. +.PP +The \fIcallProc\fR field gives a function that is called when the method is +invoked; it must never be NULL. +.PP +The \fIdeleteProc\fR field gives a function that is used to delete a +particular method, and is called when the method is replaced or removed; if +the field is NULL, it is assumed that the method's \fIclientData\fR needs no +special action to delete. +.PP +The \fIcloneProc\fR field is either a function that is used to copy a method's +\fIclientData\fR (as part of \fBTcl_CopyObjectInstance\fR) or NULL to indicate +that the \fIclientData\fR can just be copied directly. +.SS "TCL_METHODCALLPROC FUNCTION SIGNATURE" +.PP +Functions matching this signature are called when the method is invoked. +.PP +.CS +typedef int \fBTcl_MethodCallProc\fR( + ClientData \fIclientData\fR, + Tcl_Interp *\fIinterp\fR, + Tcl_ObjectContext \fIobjectContext\fR, + int \fIobjc\fR, + Tcl_Obj *const *\fIobjv\fR); +.CE +.PP +The \fIclientData\fR argument to a Tcl_MethodCallProc is the value that was +given when the method was created, the \fIinterp\fR is a place in which to +execute scripts and access variables as well as being where to put the result +of the method, and the \fIobjc\fR and \fIobjv\fR fields give the parameter +objects to the method. The calling context of the method can be discovered +through the \fIobjectContext\fR argument, and the return value from a +Tcl_MethodCallProc is any Tcl return code (e.g. TCL_OK, TCL_ERROR). +.SS "TCL_METHODDELETEPROC FUNCTION SIGNATURE" +.PP +Functions matching this signature are used when a method is deleted, whether +through a new method being created or because the object or class is deleted. +.PP +.CS +typedef void \fBTcl_MethodDeleteProc\fR( + ClientData \fIclientData\fR); +.CE +.PP +The \fIclientData\fR argument to a Tcl_MethodDeleteProc will be the same as +the value passed to the \fIclientData\fR argument to \fBTcl_NewMethod\fR or +\fBTcl_NewInstanceMethod\fR when the method was created. +.SS "TCL_CLONEPROC FUNCTION SIGNATURE" +.PP +Functions matching this signature are used to copy a method when the object or +class is copied using \fBTcl_CopyObjectInstance\fR (or \fBoo::copy\fR). +.PP +.CS +typedef int \fBTcl_CloneProc\fR( + Tcl_Interp *\fIinterp\fR, + ClientData \fIoldClientData\fR, + ClientData *\fInewClientDataPtr\fR); +.CE +.PP +The \fIinterp\fR argument gives a place to write an error message when the +attempt to clone the object is to fail, in which case the clone procedure must +also return TCL_ERROR; it should return TCL_OK otherwise. +The \fIoldClientData\fR field to a Tcl_CloneProc gives the value from the +method being copied from, and the \fInewClientDataPtr\fR field will point to +a variable in which to write the value for the method being copied to. +.SH "SEE ALSO" +Class(3), oo::class(n), oo::define(n), oo::object(n) +.SH KEYWORDS +constructor, method, object + +.\" Local variables: +.\" mode: nroff +.\" fill-column: 78 +.\" End: |