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Newsgroups: comp.lang.python
Date: Fri, 21 Dec 2012 07:36:43 -0800 (PST)
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Subject: Re: Brython - Python in the browser
From: Pierre Quentel <pierre.quentel@gmail.com>
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Xref: csiph.com comp.lang.python:35298

> Pythonic also means:
> If the implementation is hard to explain, it's a bad idea.
> What, exactly, does the sum of a string and a bolded string produce?  Can=
 you explain that easily and clearly?

Yes : a+b returns the string a+str(b)

It is exactly what you get in CPython with=20
>>> class B:
...   def __init__(self,value):
...     self.value =3D value
...   def __radd__(self,other):
...     return '%s<b>%s</b>' %(other,self.value)
...
>>> 'hello '+B('world')
'hello <b>world</b>'

> The DOM structure is, undeniably, quite verbose. But you could go for
> something with the same tree structure while a lot less wordy by
> simply returning self from lots of methods, thus allowing method
> chaining - something like this:
>=20
> https://github.com/Rosuav/Gypsum/blob/master/window.pike#L247
>=20
Hang me if I understand what this code is supposed to do ;-)
>=20
> To produce the HTML code
>=20
> <DIV>hello <B>world</B></DIV>
>=20
> you might use:
>=20
> doc.add(Tag('DIV').add('hello ').add(Tag('B').add('world')))
>=20
No, with this syntax, the result of Tag('B').add('world') is below 'hello' =
in the tree structure, not at the same level (just below Tag('DIV')) as it =
should be

In this case it's not a real problem, but it's obvious if you want to produ=
ce <ul><li>one<li>two</ul> : you would need 2 different 'add'
top =3D Tag('UL')
top.add(Tag('LI').add('one'))
top.add(Tag('LI').add('two'))

With the syntax used in Brython : UL(LI('one')+LI('two'))


>=20
> Reject the idea if you will, but do at least please consider it :)
>=20
I did in fact consider many options before proposing this one. I have done =
a lot of web programming, including a web framework, and I faced the proble=
m of generating HTML code from Python. I started with a syntax with nested =
parenthesis and chained methods returning self, only ending in ugly, unread=
able code. Once I started using <=3D for "add child" and "+" for "add broth=
er" (I first proposed it in the Python Cookbook recipe #366000, the HTMLTag=
s module) - and I've used it on fairly large projects - the result was a mu=
ch cleaner code