Re: [matplotlib-devel] switching to PS/SVG backends

[Fernando P. <Fer...@co...>]

Jochen Voss schrieb:
> Hello Steve,
> 
> On Wed, Nov 17, 2004 at 11:00:32PM +0800, Steve Chaplin wrote:
> 
>>I don't think failure to save a file should be a fatal error.
>>Perhaps PS/SVG print_figure() could raise an exception for the GUI
>>backend to catch so it can popup an error message and continue.
> 
> Even now you can probably (not tried) catch the SystemExit
> exception and prevent the program from aborting.
> Do you think raising SystemExit like
> 
>     raise SystemExit("error while writing file: permission denied")
> 
> would be good enough.  The GUI frontend could catch SystemExit,
> check whether the associated value is a string, and then display
> this string in an error message box.
> 
> What do you think?

Bad design.  Doing exception analysis based on string matching for the message 
is very brittle.  A single change in capitalization of the message can break 
things down the road.

It's _far_ better to either:

1. have the ps/svg backends do whatever cleanup they want, and then reraise 
the original exception unchanged

2. or simply make a matplotlib.SaveError exception which can be explicitly 
caught based on class matching, which is the preferred python way of doing this.

Best,

f