How can I read CPPFLAGS about conan HOT 17 CLOSED

Hi @Ed-CMI

Thanks for your question.

It is not very clear where and when you want to read this. If this is an environment variable set in the system, it would be a os.environ.get() or os.getenv() or similar.

But Conan does not set the env-vars in memory, but in script files like conanbuildenv.sh and the like.
Also env-vars can be defined, appended, prepended from different places, like in a profile file [buildenv] section, or in a recipe generate() method, depending what generator is collecting the CPPFLAGS from where (like defined from dependencies with the PkgConfigDeps generator? It is also possible to run commands without activating environment-variables by disabling the env files in self.run().

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CPPFLAGS is created when running AutoToolsDeps. I wanted to read the CPPFLAGS in the generate method to gather the list of include directories that were collected based off requires used in recipe files so I can create an option file to be used during compilation. During our integration recipe file the CPPFLAGS is getting to large and when trying to invoking the makefile the following error is generated.

    ConanException: Error 3221225477 while executing

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I see.

The AutotoolsDeps can customize its environment as defined in the docs in https://docs.conan.io/2/reference/tools/gnu/autotoolsdeps.html#customization.

Basically the environment attribute gives access to the environment definition, and allow manipulating it if desired.

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I have read thru this and will unset the variable but I need to read it first. How can I read CPPFLAG before I unset the variable? The Envvars class has a way to get environment variables but I did not see this in AutoToolsDeps.

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It is an Environment object, first step is obtain the vars as documented in https://docs.conan.io/2/reference/tools/env/environment.html#obtaining-environment-variables, something like envvars = env.vars(self, scope="build"), then you can do a get() over it (see https://docs.conan.io/2/reference/tools/env/envvars.html)

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I tried this logic before but the _include_paths kept indicating None. Am I doing something wrong?
env = Environment()
envvars = env.vars(self, scope="build")
_include_paths = envvars.get("CPPFLAGS", default=None, variable_reference=None)
print(f"Include Paths = {_include_paths}\n")

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You are instantiating a new Environnment instead of using the one from AutotoolsDeps.environment. Please check the above docs link: https://docs.conan.io/2/reference/tools/gnu/autotoolsdeps.html#customization

def generate(self):
        tc = AutotoolsDeps(self)
        tc.environment.remove("CPPFLAGS", "undesired_value")

it is the tc.environment not a new (empty) Environment object one, which is expected to return None.

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Sorry Diego but I dont understand this response. My last comment ask why this code return None instead of the data currently stored in CPPFLAGS.
env = Environment()
envvars = env.vars(self, scope="build")
_include_paths = envvars.get("CPPFLAGS", default=None, variable_reference=None)
print(f"Include Paths = {_include_paths}\n")

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You are instantiating an empty env = Environment() object. That object is empty, it doesn't contain any env-vars defined untill someone adds information to it, like env.define() or one of the other methods. Having an empty Environment object and calling env.get() over it will always return None, because that object is empty.

There is no "data currently in CPPFLAGS", the information is not stored in the global system environment variable. That information, if using AutotoolsDeps comes from the AutotoolsDeps.environment not over an empty Environment() object not connected to the AutotoolsDeps.

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Ok, Then we are back to my orginal question. How can I get the information stored in CPPFLAGS from AutoToolsDeps or is there another way to get all the includes from all the required recipe files included in the my integration recipe file?

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Ok, Then we are back to my orginal question. How can I get the information stored in CPPFLAGS from AutoToolsDeps or is there another way to get all the includes from all the required recipe files included in the my integration recipe file?

def generate(self):
        tc = AutotoolsDeps(self)
        env = tc.environment
        myenvvar = env.get("MYENVVAR")
        ...  # whatever you do with the env-var contents
        # you can also call other ``env`` methods
        
        tc.generate()

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I tried your suggestion and got the following error when using this code
tc = AutotoolsDeps(self)
env = tc.environment
_include_paths = env.get("CPPFLAGS")

ERROR: accellimrqstcoord/1.0.0.0: Error in generate() method, line 84
self.python_requires["csarbuildenvrequires"].module.csar_generate(self)
while calling 'csar_generate', line 108
_include_paths = env.get("CPPFLAGS")
AttributeError: 'Environment' object has no attribute 'get'

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Sorry, my bad, I forgot to use the EnvVars described above:

def generate(self):
        tc = AutotoolsDeps(self)
        env = tc.environment
        myenvvar = env.vars.get("MYENVVAR")
        ...  # whatever you do with the env-var contents
        # you can also call other ``env`` methods
        
        tc.generate()

Please try that and let me know.

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Same issue when using myenvvar = env.vars.get("MYENVVAR")

accellimrqstcoord/1.0.0.0: Number of Processors = 24
ERROR: accellimrqstcoord/1.0.0.0: Error in generate() method, line 84
self.python_requires["csarbuildenvrequires"].module.csar_generate(self)
while calling 'csar_generate', line 108
_include_paths = env.vars.get("CPPFLAGS")
AttributeError: 'function' object has no attribute 'get'

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I am writing the code by heart, I am not checking it, the docs contain the exact interfaces to use.

This is more tested, it shouldn't fail:

    def generate(self):
        deps = AutotoolsDeps(self)
        env = deps.environment
        vars = env.vars(self)
        cppflags = vars.get("CPPFLAGS")
        ...
        deps.generate()

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This worked. Thanks. Can you provide a link to where this is documented. I tried to check version 2.2 documentation of Conan and can't find this reference.

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• https://docs.conan.io/2/reference/tools/gnu/autotoolsdeps.html#customization defines the usage of deps.environment and returns an Environment object
• The Environment has a link, follow it for https://docs.conan.io/2/reference/tools/env/environment.html#obtaining-environment-variables, for the envvars = env.vars(self, scope="build") environment variables object
• Then you have the reference for EnvVars in https://docs.conan.io/2/reference/tools/env/envvars.html, including the .get() method

Closing the ticket as solved, thanks for the feedback!

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