Test functions return a boolean value that you can test for in the conditional parts of scopes. Test functions can be divided into built-in functions and function libraries.
另请参阅 替换函数 .
Basic test functions are implemented as built-in functions.
This is an internal function that you will typically not need.
该函数在 Qt 5.0 引入。
This function can be used to test for variables placed into the
CONFIG
variable. This is the same as scopes, but has the added advantage that a second parameter can be passed to test for the active config. As the order of values is important in
CONFIG
variables (that is, the last one set will be considered the active config for mutually exclusive values) a second parameter can be used to specify a set of values to consider. For example:
CONFIG = debug CONFIG += release CONFIG(release, debug|release):message(Release build!) #will print CONFIG(debug, debug|release):message(Debug build!) #no print
Because release is considered the active setting (for feature parsing) it will be the CONFIG used to generate the build file. In the common case a second parameter is not needed, but for specific mutual exclusive tests it is invaluable.
成功若变量
variablename
contains the value
value
; otherwise fails. It is possible to specify a regular expression for parameter
value
.
You can check the return value of this function using a scope.
例如：
contains( drivers, network ) {
# drivers contains 'network'
message( "Configuring for network build..." )
HEADERS += network.h
SOURCES += network.cpp
}
The contents of the scope are only processed if the
drivers
variable contains the value
network
. If this is the case, the appropriate files are added to the
SOURCES
and
HEADERS
变量。
成功若变量
variablename
contains a list with the specified
编号
of values; otherwise fails.
This function is used to ensure that declarations inside a scope are only processed if the variable contains the correct number of values. For example:
options = $$find(CONFIG, "debug") $$find(CONFIG, "release")
count(options, 2) {
message(Both release and debug specified.)
}
Checks whether qmake runs at the specified debug level. If yes, it returns true and prints a debug message.
Tests whether the function or variable
名称
is defined. If
type
is omitted, checks all functions. To check only variables or particular type of functions, specify
type
. It can have the following values:
Tests whether
variablename
equals the string
value
.
例如：
TARGET = helloworld
equals(TARGET, "helloworld") {
message("The target assignment was successful.")
}
This function never returns a value. qmake displays
string
as an error message to the user and exits. This function should only be used for unrecoverable errors.
例如：
error(An error has occurred in the configuration process.)
Evaluates the contents of the string using qmake syntax rules and returns true. Definitions and assignments can be used in the string to modify the values of existing variables or create new definitions.
例如：
eval(TARGET = myapp) {
message($$TARGET)
}
注意： Quotation marks can be used to delimit the string, and the return value can be discarded if it is not needed.
Tests whether a file with the given
filename
exists. If the file exists, the function succeeds; otherwise it fails. If a regular expression is specified for the filename, this function succeeds if any file matches the regular expression specified.
例如：
exists( $(QTDIR)/lib/libqt-mt* ) {
message( "Configuring for multi-threaded Qt..." )
CONFIG += thread
}
注意： "/" should be used as a directory separator, regardless of the platform in use.
Exports the current value of
variablename
from the local context of a function to the global context.
Starts a loop that iterates over all values in
list
, setting
iterate
to each value in turn. As a convenience, if
list
is 1..10 then iterate will iterate over the values 1 through 10.
例如：
LIST = 1 2 3
for(a, LIST):exists(file.$${a}):message(I see a file.$${a}!)
Tests that the value of
variablename
大于
value
. First, this function attempts a numerical comparison. If at least one of the operands fails to convert, this function does a string comparison.
例如：
ANSWER = 42
greaterThan(ANSWER, 1) {
message("The answer might be correct.")
}
It is impossible to compare two numbers as strings directly. As a workaround, construct temporary values with a non-numeric prefix and compare these.
例如：
VALUE = 123
TMP_VALUE = x$$VALUE
greaterThan(TMP_VALUE, x456): message("Condition may be true.")
另请参阅 lessThan() .
Evaluates
条件
. It is used to group boolean expressions.
例如：
if(linux-g++*|macx-g++*):CONFIG(debug, debug|release) {
message("We are on Linux or Mac OS, and we are in debug mode.")
}
Includes the contents of the file specified by
filename
into the current project at the point where it is included. This function succeeds if
filename
is included; otherwise it fails. The included file is processed immediately.
You can check whether the file was included by using this function as the condition for a scope. For example:
include( shared.pri )
OPTIONS = standard custom
!include( options.pri ) {
message( "No custom build options specified" )
OPTIONS -= custom
}
Succeeds if the file
filename
(when parsed by qmake itself) contains the variable
var
采用值
val
; otherwise fails. If you do not specify
val
, the function tests whether
var
has been assigned in the file.
This is an alias for the
CONFIG
函数。
成功若变量
variablename
is empty; otherwise fails. This is the equivalent of
count( variablename, 0 )
.
例如：
isEmpty( CONFIG ) {
CONFIG += warn_on debug
}
This is an alias for the
等于
函数。
Tests that the value of
variablename
小于
value
. Works as
greaterThan()
.
例如：
ANSWER = 42
lessThan(ANSWER, 1) {
message("The answer might be wrong.")
}
Loads the feature file (
.prf
) specified by
feature
, unless the feature has already been loaded.
Prints a message on the console. Unlike the
message
function, neither prepends text nor appends a line break.
该函数在 Qt 5.0 引入。
另请参阅 message() .
Always succeeds, and displays
string
as a general message to the user. Unlike the
error()
function, this function allows processing to continue.
message( "This is a message" )
The above line causes "This is a message" to be written to the console. The use of quotation marks is optional, but recommended.
注意：
By default, messages are written out for each Makefile generated by qmake for a given project. If you want to ensure that messages only appear once for each project, test the
build_pass
variable
in conjunction with a scope
to filter out messages during builds. For example:
!build_pass:message( "This is a message" )
Creates the directory path
dirPath
. This function is a wrapper around the
QDir::mkpath
函数。
该函数在 Qt 5.0 引入。
Evaluates
条件
. If the condition is false, qmake skips this project (and its
SUBDIRS
) when building.
注意： 还可以使用 REQUIRES variable for this purpose. However, we recommend using this function, instead.
Executes the given
命令
in a secondary shell. Succeeds if the command returns with a zero exit status; otherwise fails. You can check the return value of this function using a scope.
例如：
system("ls /bin"): HAS_BIN = TRUE
See also the replace variant of system() .
Updates the time stamp of
filename
to match the time stamp of
reference_filename
.
该函数在 Qt 5.0 引入。
移除
variablename
from the current context.
例如：
NARF = zort
unset(NARF)
!defined(NARF, var) {
message("NARF is not defined.")
}
Tests that the version number from
variablename
>=
versionNumber
. The version number is considered to be a sequence of non-negative decimal numbers delimited by '.'; any non-numerical tail of the string will be ignored. Comparison is performed segment-wise from left to right; if one version is a prefix of the other, it is considered smaller.
该函数在 Qt 5.10 引入。
Tests that the version number from
variablename
<=
versionNumber
. Works as
versionAtLeast()
.
该函数在 Qt 5.10 引入。
Always succeeds, and displays
string
as a warning message to the user.
Writes the values of
variablename
to a file with the name
filename
, each value on a separate line. If
variablename
is not specified, creates an empty file. If
mode
is
append
and the file already exists, appends to it instead of replacing it.
该函数在 Qt 5.0 引入。
Complex test functions are implemented in a library of .prf files.
Uses the PKGCONFIG mechanism to determine whether or not the given packages exist at the time of project parsing.
This can be useful to optionally enable or disable features. For example:
packagesExist(sqlite3 QtNetwork QtDeclarative) {
DEFINES += USE_FANCY_UI
}
And then, in the code:
#ifdef USE_FANCY_UI
// Use the fancy UI, as we have extra packages available
#endif
Facilitates the creation of project-wide targets similar to the
安装
target by preparing a target that iterates through all subdirectories. For example:
TEMPLATE = subdirs SUBDIRS = one two three prepareRecursiveTarget(check)
Subdirs that have
have_no_default
or
no_<target>_target
specified in their .CONFIG are excluded from this target:
two.CONFIG += no_check_target
You must add the prepared target manually to QMAKE_EXTRA_TARGETS :
QMAKE_EXTRA_TARGETS += check
To make the target global, the code above needs to be included into every subdirs subproject. In addition, to make these targets do anything, non-subdirs subprojects need to include respective code. The easiest way to achieve this is creating a custom feature file. For example:
# <project root>/features/mycheck.prf
equals(TEMPLATE, subdirs) {
prepareRecursiveTarget(check)
} else {
check.commands = echo hello user
}
QMAKE_EXTRA_TARGETS += check
The feature file needs to be injected into each subproject, for example by .qmake.conf:
# <project root>/.qmake.conf CONFIG += mycheck
该函数在 Qt 5.0 引入。
Builds a test project. If the test passes, true is returned and
config_<test>
is added to the
CONFIG
variable. Otherwise, false is returned.
To make this function available, you need to load the respective feature file:
# <project root>/project.pro load(configure)
This also sets the variable QMAKE_CONFIG_TESTS_DIR to the
config.tests
subdirectory of the project's parent directory. It is possible to override this value after loading the feature file.
Inside the tests directory, there has to be one subdirectory per test that contains a simple qmake project. The following code snippet illustrates the .pro file of the project:
# <project root>/config.tests/test/test.pro SOURCES = main.cpp LIBS += -ltheFeature # Note that the test project is built without Qt by default.
The following code snippet illustrates the main .cpp file of the project:
// <project root>/config.tests/test/main.cpp
#include <TheFeature/MainHeader.h>
int main() { return featureFunction(); }
The following code snippet shows the invocation of the test:
# <project root>/project.pro qtCompileTest(test)
If the test project is built successfully, the test passes.
The test results are automatically cached, which also makes them available to all subprojects. It is therefore recommended to run all configuration tests in the top-level project file.
To suppress the re-use of cached results, pass
CONFIG+=recheck
to qmake.
另请参阅 load() .
该函数在 Qt 5.0 引入。
Checks whether the Qt module specified by
名称
is present. For a list of possible values, see
QT
.
This function was introduced in Qt 5.0.1.