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authorKen Martin <ken.martin@kitware.com>2009-06-12 14:07:05 (GMT)
committerKen Martin <ken.martin@kitware.com>2009-06-12 14:07:05 (GMT)
commita73071ca175c70db95271688ef9c7711e700f9a7 (patch)
tree7845929f87622edbe30e9009e80aa3c6016fe5c1 /Source/cmIfCommand.h
parent7e03edf1df6875b80f53b66dce5ac4f42a49394d (diff)
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ENH: modified the if command to address bug 9123 some
Diffstat (limited to 'Source/cmIfCommand.h')
-rw-r--r--Source/cmIfCommand.h71
1 files changed, 67 insertions, 4 deletions
diff --git a/Source/cmIfCommand.h b/Source/cmIfCommand.h
index 68d0f67..a55c982 100644
--- a/Source/cmIfCommand.h
+++ b/Source/cmIfCommand.h
@@ -191,6 +191,71 @@ public:
"examples. Where there are nested parenthesis the innermost are "
"evaluated as part of evaluating the expression "
"that contains them."
+ "\n"
+
+ "The if statement was written fairly early in CMake's history "
+ "and it has some convenience features that may be confusing for "
+ "new users. The if statement reduces operations until there is "
+ "a single remaining value, at that point if the case "
+ "insensitive value is: ON, 1, YES, TRUE, Y it returns true, if "
+ "it is OFF, 0, NO, FALSE, N, NOTFOUND, *-NOTFOUND, IGNORE it "
+ "will return false. \n"
+
+ "This is fairly reasonable. The convenience feature that makes "
+ "it more confusing is how CMake handles values that do not "
+ "match the true or false list. Those values are treated as "
+ "variables and are dereferenced even though they do not have "
+ "the required ${} syntax. This means that if you write\n"
+
+ " if (boobah)\n"
+
+ "CMake will treat it as if you wrote \n"
+
+ " if (${boobah})\n"
+
+ "likewise if you write \n"
+
+ " if (fubar AND sol)\n"
+
+ "CMake will conveniently treat it as \n"
+
+ " if (\"${fubar}\" AND \"${sol}\")\n"
+
+ "The later is really the correct way to write it, but the "
+ "former will work as well. Only some operations in the if "
+ "statement have this special handling of arguments. The "
+ "specific details follow: \n"
+
+ "1) The left hand argument to MATCHES is first checked to see "
+ "if it is a defined variable, if so the variable's value is "
+ "used, otherwise the original value is used. \n"
+
+ "2) If the left hand argument to MATCHES is missing it returns "
+ "false without error \n"
+
+ "3) Both left and right hand arguments to LESS GREATER EQUAL "
+ "are independently tested to see if they are defined variables, "
+ "if so their defined values are used otherwise the original "
+ "value is used. \n"
+
+ "4) Both left and right hand arguments to STRLESS STREQUAL "
+ "STRGREATER are independently tested to see if they are defined "
+ "variables, if so their defined values are used otherwise the "
+ "original value is used. \n"
+
+ "5) Both left and right hand argumemnts to VERSION_LESS "
+ "VERSION_EQUAL VERSION_GREATER are independently tested to see "
+ "if they are defined variables, if so their defined values are "
+ "used otherwise the original value is used. \n"
+
+ "6) The right hand argument to NOT is tested to see if it is a "
+ "boolean constant, if so the value is used, otherwise it is "
+ "assumed to be a variable and it is dereferenced. \n"
+
+ "7) The left and right hand arguments to AND OR are "
+ "independently tested to see if they are boolean constants, if "
+ "so they are used as such, otherwise they are assumed to be "
+ "variables and are dereferenced. \n"
;
}
@@ -198,15 +263,13 @@ public:
// arguments were valid, and if so, was the response true. If there is
// an error, the errorString will be set.
static bool IsTrue(const std::vector<std::string> &args,
- std::string &errorString, cmMakefile *mf);
+ std::string &errorString, cmMakefile *mf,
+ cmake::MessageType &status);
// Get a definition from the makefile. If it doesn't exist,
// return the original string.
static const char* GetVariableOrString(const char* str,
const cmMakefile* mf);
- static const char* GetVariableOrNumber(const char* str,
- const cmMakefile* mf);
-
cmTypeMacro(cmIfCommand, cmCommand);
};