[mod_python] using nested blocks in psp

Mon Jun 12 04:04:13 EDT 2006

cloc3 wrote:
> I'm a newbie in python, and I'm fighting against nested blocks in psp.
> Thats a little example with a funny behaviour:
> [code]
> <html>
> <form>
> <select name="List">
> <!--makes a list with a loop -->
>
> <%
> for i in range(50, 350, 50):
>  if 'List' in form and int(form['List'])==i:
>   sel="selected"
>  else:
>   sel="pippo"
>  %><option value="<%=i%>" <%=sel%> ><%=i%> </option>
>  <%
> %>
> </select>
> <input type="submit" value="return"/>
> </form>
> </html>
> [/code]
> In my intention, the for instruction have to run two operation:
>  first: the if instruction
>  second: to print the option tag on the html page.
>
> Instead, the real behaviour is depending on the result of the control
> in the if:
>  if the control is true, the option tag is not printed, and the for
> instruction goes to the successive step.
>  if the control is false, the option is correctly printed.
>
> I don't understand the reason of this behaviour.
> Which is the right way to control the nested block instructions in psp?

PSP as implemented by mod_python is fussy about how many spaces are
used in indents. Use either 8 space or tab indents. If you don't want
to do that, you will need to use comment hints to help PSP understand
what level of indenting you are using. See:

  http://www.modpython.org/pipermail/mod_python/2005-May/018102.html

Comment hints may still be needed in certain cases to turn off scopes
even if 8 space or tab indents are needed so it is good to understand
what they are about.

Also ask further questions on mod_python user mailing list as you will
in general get better responses there.

Graham