[Python-Dev] PEP-498: Literal String Formatting

Alexander Walters tritium-list at sdamon.com
Tue Aug 11 17:52:37 CEST 2015


On 8/11/2015 11:28, Wes Turner wrote:
>
>
> On Aug 11, 2015 10:19 AM, "Wes Turner" <wes.turner at gmail.com 
> <mailto:wes.turner at gmail.com>> wrote:
>
> - [ ] review all string interpolation (for "injection")
>   * [ ] review every '%'
>   * [ ] review every ".format()"
>   * [ ] review every f-string (AND LOCALS AND GLOBALS)
>   * every os.system, os.exec*, subprocess.Popen
>   * every unclosed tag
>   * every unescaped control character
>
> This would create work we don't need.
>
> Solution: __str_shell_ escapes, adds slashes, and quotes. __str__SQL__ 
> refs a global list of reserved words.
>
I don't understand why % and .format got interjected into this.

If you are mentioning them as 'get the unprocessed version of any string 
formatting', that is a bad idea, and not needed, since you already have 
an unprocessed string object.  Assuming the method were named 
"hypothetical":

 >>> 'foo bar'.hypothetical()      # returns 'foo bar'
 >>> '{0} bar'.format('foo').hypothetical()      # returns 'foo bar'
 >>> ('%s bar' % ('foo',)).hypothetical()     # returns 'foo bar'
 >>> f'{foo} bar'.hypothetical()     # returns '{foo} bar', prime for 
translation.

could gettext not be modified to create the same AST as f'{foo} bar' 
when it is translated to '{foo} le bar.' and inject it back into the 
runtime?
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