[PATCH] build/data: Don't expand python functions before execution [API change]

[PATCH] build/data: Don't expand python functions before execution [API change]

[Richard Purdie]

Right now, if you have some python code like:

X = "a"

def somefunction(d):
    d.setVar("X", "b")
    d.setVar("Y", "${X}")

then any sane person would expect that Y = "b" at the end of the
function. This is not the case, Y = "a".

This is due to the python function being expanded before execution, the
executed code would read d.setVar("Y", "a"). This understandably
confuses people, it also makes it near impossible to write ${} in a
python function without unintended things happening.

I think there is general agreement we should fix this and standardise
on non-expansion of python functions. We already don't expand anonymous
python (mostly).

I've checked OE-Core with buildhistory before and after this change and
there were a small number of issues this exposed which I've sent
patches for.

I propose we default to not expanding python code and then deal with
any consequences from that if/as/where identified. This will improve
new user understanding and usability of the system, it also allows
several long standing weird expansion issues to be fixed.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

diff --git a/bitbake/lib/bb/build.py b/bitbake/lib/bb/build.py
index 52a4916..b7c49eb 100644
--- a/bitbake/lib/bb/build.py
+++ b/bitbake/lib/bb/build.py
@@ -239,7 +239,7 @@ def exec_func_python(func, d, runfile, cwd=None):
     """Execute a python BB 'function'"""
 
     bbfile = d.getVar('FILE', True)
-    code = _functionfmt.format(function=func, body=d.getVar(func, True))
+    code = _functionfmt.format(function=func, body=d.getVar(func, False))
     bb.utils.mkdirhier(os.path.dirname(runfile))
     with open(runfile, 'w') as script:
         bb.data.emit_func_python(func, script, d)
diff --git a/bitbake/lib/bb/data.py b/bitbake/lib/bb/data.py
index 1f1f0d2..86ad4ed 100644
--- a/bitbake/lib/bb/data.py
+++ b/bitbake/lib/bb/data.py
@@ -308,7 +308,7 @@ def emit_func_python(func, o=sys.__stdout__, d = init()):
 
     write_func(func, o, True)
     pp = bb.codeparser.PythonParser(func, logger)
-    pp.parse_python(d.getVar(func, True))
+    pp.parse_python(d.getVar(func, False))
     newdeps = pp.execs
     newdeps |= set((d.getVarFlag(func, "vardeps", True) or "").split())
     seen = set()

Re: [Openembedded-architecture] [PATCH] build/data: Don't expand python functions before execution [API change]

[Burton, Ross]

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On 2 February 2016 at 14:07, Richard Purdie <
richard.purdie@linuxfoundation.org> wrote:

> I propose we default to not expanding python code and then deal with
> any consequences from that if/as/where identified. This will improve
> new user understanding and usability of the system, it also allows
> several long standing weird expansion issues to be fixed.
>

As someone who has had to write classes that do "$" + "{FOO}", this gets a
massive +1 from me.

Ross

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Re: [Openembedded-architecture] [PATCH] build/data: Don't expand python functions before execution [API change]

[Olof Johansson]

On 16-02-02 14:41 +0000, Burton, Ross wrote:
> On 2 February 2016 at 14:07, Richard Purdie <
> richard.purdie@linuxfoundation.org> wrote:
> 
> > I propose we default to not expanding python code and then deal with
> > any consequences from that if/as/where identified. This will improve
> > new user understanding and usability of the system, it also allows
> > several long standing weird expansion issues to be fixed.
> >
> 
> As someone who has had to write classes that do "$" + "{FOO}", this gets a
> massive +1 from me.

Indeed, it's a very welcome change from my point of view! +1

-- 
olofjn

Re: [PATCH] build/data: Don't expand python functions before execution [API change]

[Christopher Larson]

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On Tuesday, February 2, 2016, Richard Purdie <
richard.purdie@linuxfoundation.org> wrote:

> Right now, if you have some python code like:
>
> X = "a"
>
> def somefunction(d):
>     d.setVar("X", "b")
>     d.setVar("Y", "${X}")
>
> then any sane person would expect that Y = "b" at the end of the
> function. This is not the case, Y = "a".
>
> This is due to the python function being expanded before execution, the
> executed code would read d.setVar("Y", "a"). This understandably
> confuses people, it also makes it near impossible to write ${} in a
> python function without unintended things happening.
>
> I think there is general agreement we should fix this and standardise
> on non-expansion of python functions. We already don't expand anonymous
> python (mostly).
>
> I've checked OE-Core with buildhistory before and after this change and
> there were a small number of issues this exposed which I've sent
> patches for.
>
> I propose we default to not expanding python code and then deal with
> any consequences from that if/as/where identified. This will improve
> new user understanding and usability of the system, it also allows
> several long standing weird expansion issues to be fixed.
>
> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org
> <javascript:;>>
>

I absolutely support this. It should reduce confusion with no loss of
functionality.

Acked-by: Christopher Larson <kergoth@gmail.com>


-- 
Christopher Larson
kergoth at gmail dot com
Founder - BitBake, OpenEmbedded, OpenZaurus
Maintainer - Tslib
Senior Software Engineer, Mentor Graphics

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Re: [PATCH] build/data: Don't expand python functions before execution [API change]

[Khem Raj]

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> On Feb 2, 2016, at 6:07 AM, Richard Purdie <richard.purdie@linuxfoundation.org> wrote:
> 
> Right now, if you have some python code like:
> 
> X = "a"
> 
> def somefunction(d):
>    d.setVar("X", "b")
>    d.setVar("Y", "${X}")
> 
> then any sane person would expect that Y = "b" at the end of the
> function. This is not the case, Y = "a".
> 
> This is due to the python function being expanded before execution, the
> executed code would read d.setVar("Y", "a"). This understandably
> confuses people, it also makes it near impossible to write ${} in a
> python function without unintended things happening.
> 
> I think there is general agreement we should fix this and standardise
> on non-expansion of python functions. We already don't expand anonymous
> python (mostly).
> 
> I've checked OE-Core with buildhistory before and after this change and
> there were a small number of issues this exposed which I've sent
> patches for.
> 
> I propose we default to not expanding python code and then deal with
> any consequences from that if/as/where identified. This will improve
> new user understanding and usability of the system, it also allows
> several long standing weird expansion issues to be fixed.

I support this too. Additionally, it will be a nice to document this if it has not been done
thus far.

> 
> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
> 
> diff --git a/bitbake/lib/bb/build.py b/bitbake/lib/bb/build.py
> index 52a4916..b7c49eb 100644
> --- a/bitbake/lib/bb/build.py
> +++ b/bitbake/lib/bb/build.py
> @@ -239,7 +239,7 @@ def exec_func_python(func, d, runfile, cwd=None):
>     """Execute a python BB 'function'"""
> 
>     bbfile = d.getVar('FILE', True)
> -    code = _functionfmt.format(function=func, body=d.getVar(func, True))
> +    code = _functionfmt.format(function=func, body=d.getVar(func, False))
>     bb.utils.mkdirhier(os.path.dirname(runfile))
>     with open(runfile, 'w') as script:
>         bb.data.emit_func_python(func, script, d)
> diff --git a/bitbake/lib/bb/data.py b/bitbake/lib/bb/data.py
> index 1f1f0d2..86ad4ed 100644
> --- a/bitbake/lib/bb/data.py
> +++ b/bitbake/lib/bb/data.py
> @@ -308,7 +308,7 @@ def emit_func_python(func, o=sys.__stdout__, d = init()):
> 
>     write_func(func, o, True)
>     pp = bb.codeparser.PythonParser(func, logger)
> -    pp.parse_python(d.getVar(func, True))
> +    pp.parse_python(d.getVar(func, False))
>     newdeps = pp.execs
>     newdeps |= set((d.getVarFlag(func, "vardeps", True) or "").split())
>     seen = set()
> 
> 
> --
> _______________________________________________
> bitbake-devel mailing list
> bitbake-devel@lists.openembedded.org
> http://lists.openembedded.org/mailman/listinfo/bitbake-devel


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