[Mesa-dev] [PATCH 19/26] python: Don't abuse hex()

[Eric Engestrom]

On Thursday, 2018-07-05 15:17:50 +0200, Mathieu Bridon wrote:
> The hex() builtin returns a string containing the hexa-decimal
> representation of an integer.
> 
> When the argument is not an integer, then the function calls that
> object's __hex__() method, if one is defined. That method is supposed to
> return a string.
> 
> While that's not explicitly documented, that string is supposed to be a
> valid hexa-decimal representation for a number. Python 2 doesn't enforce
> this though, which is why we got away with returning things like
> 'NIR_TRUE' which are not numbers.
> 
> In Python 3, the hex() builtin instead calls an object's __index__()
> method, which itself must return an integer. That integer is then
> automatically converted to a string with its hexa-decimal representation
> by the rest of the hex() function.
> 
> As a result, we really can't make this compatible with Python 3 as it
> is.
> 
> The solution is to stop using the hex() builtin, and instead use a hex()
> object method, which can return whatever we want, in Python 2 and 3.
> 
> Signed-off-by: Mathieu Bridon <bochecha at daitauha.fr>

Reviewed-by: Eric Engestrom <eric.engestrom at intel.com>

> ---
>  src/compiler/nir/nir_algebraic.py | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/src/compiler/nir/nir_algebraic.py b/src/compiler/nir/nir_algebraic.py
> index 63a7cb5ad1..d53a9869de 100644
> --- a/src/compiler/nir/nir_algebraic.py
> +++ b/src/compiler/nir/nir_algebraic.py
> @@ -88,7 +88,7 @@ class Value(object):
>  static const ${val.c_type} ${val.name} = {
>     { ${val.type_enum}, ${val.bit_size} },
>  % if isinstance(val, Constant):
> -   ${val.type()}, { ${hex(val)} /* ${val.value} */ },
> +   ${val.type()}, { ${val.hex()} /* ${val.value} */ },
>  % elif isinstance(val, Variable):
>     ${val.index}, /* ${val.var_name} */
>     ${'true' if val.is_constant else 'false'},
> @@ -142,7 +142,7 @@ class Constant(Value):
>           assert self.bit_size == 0 or self.bit_size == 32
>           self.bit_size = 32
>  
> -   def __hex__(self):
> +   def hex(self):
>        if isinstance(self.value, (bool)):
>           return 'NIR_TRUE' if self.value else 'NIR_FALSE'
>        if isinstance(self.value, integer_types):
> -- 
> 2.17.1
> 
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