From e4e14e856800020febf770221cb0593fa72e5c1b Mon Sep 17 00:00:00 2001 From: Brad King Date: Fri, 14 Jan 2011 18:28:56 -0500 Subject: [PATCH 1/2] Replace misleading example in the if() documentation (#10773) Remove the example explained by the misleading phrase "CMake will treat it as if you wrote". This was originally added by commit a73071ca (modified the if command to address bug 9123 some, 2009-06-12). Later related information elsewhere in the documentation was corrected and made precise by commit cb185d93 (Fix if() command and CMP0012 OLD/NEW behavior, 2009-10-27) but the misleading example was not corrected. Replace the example with a correct one that more directly covers the case that typically surprises newcomers. Avoid recommending a "correct" way to write code because this behavior is always specific to each case. Also update the main documentation of the behavior to be more explicit. --- Source/cmIfCommand.h | 59 +++++++++++++++++++------------------------- 1 file changed, 25 insertions(+), 34 deletions(-) diff --git a/Source/cmIfCommand.h b/Source/cmIfCommand.h index 107a8923bc..7c4baba4e4 100644 --- a/Source/cmIfCommand.h +++ b/Source/cmIfCommand.h @@ -125,10 +125,13 @@ public: "True if the constant is 1, ON, YES, TRUE, Y, or a non-zero number. " "False if the constant is 0, OFF, NO, FALSE, N, IGNORE, \"\", " "or ends in the suffix '-NOTFOUND'. " - "Named boolean constants are case-insensitive." + "Named boolean constants are case-insensitive. " + "If the argument is not one of these constants, " + "it is treated as a variable:" "\n" " if()\n" - "True if the variable's value is not a false constant." + "True if the variable is defined to a value that is not a false " + "constant. False otherwise. " "\n" " if(NOT )\n" "True if the expression is not true." @@ -199,38 +202,26 @@ public: "that contains them." "\n" - "The if statement was written fairly early in CMake's history " - "and it has some convenience features that are worth covering. " - "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 sometimes " - "throws new authors 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" + "The if command was written very early in CMake's history, predating " + "the ${} variable evaluation syntax, and for convenience evaluates " + "variables named by its arguments. " + "Note that normal variable evaluation with ${} applies before the " + "if command even receives the arguments. " + "Therefore code like\n" + " set(var1 OFF)\n" + " set(var2 \"var1\")\n" + " if(${var2})\n" + "appears to the if command as\n" + " if(var1)\n" + "and is evaluated according to the if() case " + "documented above. " + "The result is OFF which is false. " + "However, if we remove the ${} from the example then the command sees\n" + " if(var2)\n" + "which is true because var2 is defined to \"var1\" which is not " + "a false constant." + "\n" + "Automatic evaluation applies in the other cases as follows:\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 " From 7d9b903756bcb5a7e210b78c5ab9551dab6ab538 Mon Sep 17 00:00:00 2001 From: Brad King Date: Mon, 17 Jan 2011 09:43:41 -0500 Subject: [PATCH 2/2] Clarify auto-dereference cases in if() command (#11701) Show "" explicitly in if() case documentation whenever auto-dereferencing occurs. Reference its presence from the explanation at the bottom. --- Source/cmIfCommand.h | 34 ++++++++++++++-------------------- 1 file changed, 14 insertions(+), 20 deletions(-) diff --git a/Source/cmIfCommand.h b/Source/cmIfCommand.h index 7c4baba4e4..4996bc4007 100644 --- a/Source/cmIfCommand.h +++ b/Source/cmIfCommand.h @@ -166,32 +166,25 @@ public: "Behavior is well-defined only for full paths.\n" " if(IS_ABSOLUTE path)\n" "True if the given path is an absolute path.\n" - " if(variable MATCHES regex)\n" - " if(string MATCHES regex)\n" + " if( MATCHES regex)\n" "True if the given string or variable's value matches the given " "regular expression.\n" - " if(variable LESS number)\n" - " if(string LESS number)\n" - " if(variable GREATER number)\n" - " if(string GREATER number)\n" - " if(variable EQUAL number)\n" - " if(string EQUAL number)\n" + " if( LESS )\n" + " if( GREATER )\n" + " if( EQUAL )\n" "True if the given string or variable's value is a valid number and " "the inequality or equality is true.\n" - " if(variable STRLESS string)\n" - " if(string STRLESS string)\n" - " if(variable STRGREATER string)\n" - " if(string STRGREATER string)\n" - " if(variable STREQUAL string)\n" - " if(string STREQUAL string)\n" + " if( STRLESS )\n" + " if( STRGREATER )\n" + " if( STREQUAL )\n" "True if the given string or variable's value is lexicographically " "less (or greater, or equal) than the string or variable on the right.\n" - " if(version1 VERSION_LESS version2)\n" - " if(version1 VERSION_EQUAL version2)\n" - " if(version1 VERSION_GREATER version2)\n" + " if( VERSION_LESS )\n" + " if( VERSION_EQUAL )\n" + " if( VERSION_GREATER )\n" "Component-wise integer version number comparison (version format is " "major[.minor[.patch[.tweak]]]).\n" - " if(DEFINED variable)\n" + " if(DEFINED )\n" "True if the given variable is defined. It does not matter if the " "variable is true or false just if it has been set.\n" " if((expression) AND (expression OR (expression)))\n" @@ -204,7 +197,7 @@ public: "The if command was written very early in CMake's history, predating " "the ${} variable evaluation syntax, and for convenience evaluates " - "variables named by its arguments. " + "variables named by its arguments as shown in the above signatures. " "Note that normal variable evaluation with ${} applies before the " "if command even receives the arguments. " "Therefore code like\n" @@ -221,7 +214,8 @@ public: "which is true because var2 is defined to \"var1\" which is not " "a false constant." "\n" - "Automatic evaluation applies in the other cases as follows:\n" + "Automatic evaluation applies in the other cases whenever the " + "above-documented signature accepts :\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 "