fix cwd issues in set_version() evaluation

[memsharded]

Changelog: Bugfix: Make sure set_version() runs in the conanfile.py folder, not in the current folder, so relative paths are not broken if executing from a different location.
Docs: conan-io/docs#1490

Close: #6129

[danimtb]

I think it is consistent with the behavior in current commands

[jgsogo]

I'm not sure about this change. Before you were able to use os.getcwd() (wherever the conan export was called from) or os.path.dirname(__file__) if you really want to build a path starting from the conanfile.py.

With this change we've lost the first alternative.... and we've just won the ability to be less explicit about the path.

---

I'm aware about the python-requires issue, but it can be worked around passing the os.path.dirname(__file__) to the function (copied from #6129):

base_recipe = python_requires("bundle_conanfile/1.0@asaljo/testing")

class Builder(base_recipe.get_conanfile()):
  name = "test"
  version = base_recipe.get_bundle_version(os.path.dirname(__file__))

[memsharded]

I'm aware about the python-requires issue, but it can be worked around passing the os.path.dirname(file) to the function

That is part of the issue, we don't want to have a custom method/function, we want to inherit the set_version() method, and you cannot pass arguments to it. Take into accounts that python_requires are going to be move to a declarative interface, where the module is no longer available at recipe parse time.

[jgsogo]

IMO it is never a good idea to change the current-working-folder. Why not use the same strategy as we do for the source_folder or the build_folder and provide a xxxxx_folder which is the path to the folder where the recipe being built is located? It would fulfill the requirement too.

[memsharded]

IMO it is never a good idea to change the current-working-folder. Why not use the same strategy as we do for the source_folder or the build_folder and provide a xxxxx_folder which is the path to the folder where the recipe being built is located? It would fulfill the requirement too.

Conan already changes the working directory for other methods, like source(), build() and package(). This is nothing new, has been there since always.

For a python_require, it is not possible to use something like:

def set_version(self):
     self.version = load(os.path.join(self.recipe_folder, "version.txt")

Because that self.recipe_folder would still be the folder of the python_require, not the consumer of the python_require. Python requires are shared among their consumers too.

I still need to figure out a use case in which the result of conan export or conan create will be different depending on your current location. As I see it, the behavior of the recipe should be completely invariant, the result should always be the same if you do conan export pkg_folder, or conan export . or conan export path/to/myconanfile.py. If you want to inject version information from the outside of the recipe, you should probably skip the set_version() method and use conan export <path> version@user/channel form.

[jgsogo]

IMO it is never a good idea to change the current-working-folder. Why not use the same strategy as we do for the source_folder or the build_folder and provide a xxxxx_folder which is the path to the folder where the recipe being built is located? It would fulfill the requirement too.

Conan already changes the working directory for other methods, like source(), build() and package(). This is nothing new, has been there since always.

It doesn't mean it is a good idea to do it.

I don't come across many recipes with os.getcwd() (zero matches in conan-center-index) and I find many with things like self.souce_folder or self.build_folder.

For a python_require, it is not possible to use something like:

def set_version(self):
     self.version = load(os.path.join(self.recipe_folder, "version.txt")

Because that self.recipe_folder would still be the folder of the python_require, not the consumer of the python_require. Python requires are shared among their consumers too.

The self.recipe_folder should be the folder of the package being built, exactly the same as the self.source_folder or the slef.build_folder. If we use a python_requires like:

# Here it goes my python_requires recipe
class MyRecipe(ConanFile):
    ...

def get_conanfile():
    class BaseConan(ConanFile):

        def build(self):
            .... os.path.join(self.build_folder, "CMakeLists.txt")

it will use the build_folder of the package being built, it won't raise because a python_requires doesn't have the concept of build or package or binaries... and the build_folder doesn't make sense for it.

I still need to figure out a use case in which the result of conan export or conan create will be different depending on your current location. As I see it, the behavior of the recipe should be completely invariant, the result should always be the same if you do conan export pkg_folder, or conan export . or conan export path/to/myconanfile.py. If you want to inject version information from the outside of the recipe, you should probably skip the set_version() method and use conan export <path> version@user/channel form.

Totally agree, but let's do it with an explicit attribute that always has the same value rather than with a os.getcwd() call that returns different values depending on where it is written. That's my only point.

---

Full picture: explicit, no current working directory, lovely 😄

class MyRecipe(ConanFile):
    ...

def get_conanfile():

    class BaseConan(ConanFile):

        def set_version(self):
             self.version = load(os.path.join(self.recipe_folder, "version.txt")

        def build(self):
            .... os.path.join(self.build_folder, "CMakeLists.txt")

[memsharded]

Yes, I see the value of self.version = load(os.path.join(self.recipe_folder, "version.txt"), lets make a decision @lasote to see if possible for 1.21

[memsharded]

Last changes contain the self.recipe_folder solution, but can be reverted if decided otherwise.

[jgsogo]

I like it with the self.recipe_folder.

Not sure about the scope of the variable, but better to start with the minimal possible and expand it if needed.

[lasote]

The docs are needed. We need to mention somewhere the recipe_folder.