better way than: myPage += 'more html' , ...

**Alan Kennedy** · Jul 18 '05, 12:06 AM

Re: better way than: myPage += 'more html' , ...

Gobo Borz wrote:
[color=blue]
> I remember reading somewhere that building the string with successive
> "+=" statements is inefficient, but I don't know any alternatives, and
> my search attempts came up empty. Is there a better, more efficient way
> to do it than this:
>
> #---------------------------------
> htmlPage = "<html><header> </header><body>"
> htmlPage += "more html"
> ...
> htmlPage += "even more html"
> ...
> htmlPage += "</body></html>"
> print htmlPage
> #-------------------------------------[/color]

Best to do something like

#---------------------------------

htmlbits = []
htmlbits.append ("<html><header ></header><body>")
htmlbits.append ("more html")
# ...
htmlbits.append ("even more html")
# ...
htmlbits.append ("</body></html>")

# And now for the non-intuitive bit
print "".join(htmlbit s)

#---------------------------------

HTH,

--
alan kennedy
-----------------------------------------------------
check http headers here: http://xhaus.com/headers
email alan: http://xhaus.com/mailto/alan

**Anthony Baxter** · Jul 18 '05, 12:06 AM

Re: better way than: myPage += 'more html' , ...

[color=blue][color=green][color=darkred]
>>> Gobo Borz wrote[/color][/color]
> I remember reading somewhere that building the string with successive
> "+=" statements is inefficient, but I don't know any alternatives, and
> my search attempts came up empty. Is there a better, more efficient way
> to do it than this:
>
> #---------------------------------
> htmlPage = "<html><header> </header><body>"
> htmlPage += "more html"
> ...
> htmlPage += "even more html"
> ...
> htmlPage += "</body></html>"
> print htmlPage
> #-------------------------------------[/color]

Instead, build up a list of strings, then join them all at
the end - this way, the system only has to allocate the
space once. Much quicker.

#---------------------------------
htmlPage = []
htmlPage.append ("<html><header ></header><body>")
htmlPage.append ("more html")
...
htmlPage.append ("even more html")
...
htmlPage.append ("</body></html>")
page = ''.join(htmlPag e)
print page
#-------------------------------------

Anthony

**Andy Jewell** · Jul 18 '05, 12:06 AM

Re: better way than: myPage += 'more html' , ...

On Wednesday 25 Jun 2003 5:20 pm, Gobo Borz wrote:[color=blue]
> Hi everyone,
>
> I have a python cgi program that uses print statements to write html.
> The program has grown, and for reasons I won't bore you with, I need to
> build the page in a string and "print" it at once.
>
> I remember reading somewhere that building the string with successive
> "+=" statements is inefficient, but I don't know any alternatives, and
> my search attempts came up empty. Is there a better, more efficient way
> to do it than this:
>
> #---------------------------------
> htmlPage = "<html><header> </header><body>"
> htmlPage += "more html"
> ...
> htmlPage += "even more html"
> ...
> htmlPage += "</body></html>"
> print htmlPage
> #-------------------------------------
>
> Thanks, Gobo[/color]

An easy way, which requires little changes tou your code would be to use a
list and join it up into a string in one go at the end:

-----------8<--------------
htmlPage=["<html><header> </header><body>\n "]
htmlPage.append ("more html\n")
....
htmlPage.append ("more html\n")
....
htmlPage.append ("<\body><\html >\n")
htmlDoc="".join (htmlPage)
-----------8<--------------

This is more efficient, as the string joining is done all at the same time,
rather than in little chunks.

hope that helps
-andyj

**Gobo Borz** · Jul 18 '05, 12:06 AM

Re: better way than: myPage += 'more html' , ...

Thanks Alan, Anthony, and Andy! B's thru Z's need not respond, I have
my answer.

--Gobo

Gobo Borz wrote:[color=blue]
> Hi everyone,
>
> I have a python cgi program that uses print statements to write html.
> The program has grown, and for reasons I won't bore you with, I need to
> build the page in a string and "print" it at once.
>
> I remember reading somewhere that building the string with successive
> "+=" statements is inefficient, but I don't know any alternatives, and
> my search attempts came up empty. Is there a better, more efficient way
> to do it than this:
>
> #---------------------------------
> htmlPage = "<html><header> </header><body>"
> htmlPage += "more html"
> ...
> htmlPage += "even more html"
> ...
> htmlPage += "</body></html>"
> print htmlPage
> #-------------------------------------
>
> Thanks, Gobo
>[/color]

**Gobo Borz** · Jul 18 '05, 12:06 AM

Re: better way than: myPage += 'more html' , ...

Thanks, that opens up a world of possibilities I haven't began to
explore. In general, I'm not fond of templating systems because of the
overhead, but it seems as your suggestion might be fast, since it uses
ordinary string substitution.

--Gobo

mirko-lists@zeibig.ne t wrote:[color=blue]
> In article <3EF9CBCB.90305 @yahoo.com>, Gobo Borz wrote:
>[color=green]
>>I remember reading somewhere that building the string with successive
>>"+=" statements is inefficient, but I don't know any alternatives, and
>>my search attempts came up empty. Is there a better, more efficient way
>>to do it than this:
>>
>>#---------------------------------
>>htmlPage = "<html><header> </header><body>"
>>htmlPage += "more html"
>>...
>>htmlPage += "even more html"
>>...
>>htmlPage += "</body></html>"
>>print htmlPage
>>#-------------------------------------[/color]
>
> Hello Gobo,
>
> you may use the list solution provided in the former chapters. Some other
> solution would be to use string substitution:
> --------- snip -----------
> htmlPage = """
> <html>
> <head>
> <title>%(title) s</title>
> </head>
> <body>
> <h1>%(title)s </h1>
> %(body)s
> </body>
> </html>
> """
>
> body = []
> body.append("<p >my first snippet</p>")
> body.append("<u l>")
> for in range(10):
> body.append(""" <li>%s. entry</li>""" % i)
> body.append("</ul>")
>
> contents = { "title": "My Foopage",
> "body": "\n".join(b ody) }
>
> print htmlPage % contents
> -------- snap -------------
>
> This type of substitution goes for a very simple templating system.
>
> Best Regards
> Mirko
>[/color]

**Gerrit Holl** · Jul 18 '05, 12:06 AM

Re: better way than: myPage += 'more html' , ...

Gobo Borz wrote:[color=blue]
> I have a python cgi program that uses print statements to write html.
> The program has grown, and for reasons I won't bore you with, I need to
> build the page in a string and "print" it at once.[/color]

Another way, which has not yet been mentioned but which I like much,
is the cStringIO module. You can write to a string as if it is a
file:

0 >>> import cStringIO
1 >>> mystr = cStringIO.Strin gIO()
2 >>> mystr.write("<h tml")
3 >>> mystr.write("<b ody>")
4 >>> mystr.write("<h 1>Header</h1>")
5 >>> mystr.write("<p >Hello, world!</p>")
6 >>> mystr.write("</body></html>")
10 >>> mystr.getvalue( )
'<html<body><h1 >Header</h1><p>Hello, world!</p></body></html>'

The cStringIO module is documented at:

Python 3.16 documentation

http://www.python.org/dev/doc/devel/lib/module-StringIO.html

The official Python documentation.

cStringIO is a faster C implementation with the same API.

yours,
Gerrit.

--
196. If a man put out the eye of another man, his eye shall be put out.
-- 1780 BC, Hammurabi, Code of Law
--
Asperger Syndroom - een persoonlijke benadering:

http://people.nl.linux.org/~gerrit/

Het zijn tijden om je zelf met politiek te bemoeien:

Maak Nederland betaalbaar - SP - Socialistische Partij

http://www.sp.nl/

De website van de Socialistische Partij (SP) in Nederland: Informatie, nieuws, agenda en publicaties.

**Max M** · Jul 18 '05, 12:06 AM

Re: better way than: myPage += 'more html' , ...

#Gobo Borz wrote:
#> Thanks, that opens up a world of possibilities I haven't began to
#> explore. In general, I'm not fond of templating systems because of the
#> overhead, but it seems as your suggestion might be fast, since it uses
#> ordinary string substitution.
#

Often an adapter is a good choice:

class HtmlViewAdapter :

"""
Base class that Adapts any object to html output.
"""

def __init__(self, obj):
self._obj = obj

def __getattr__(sel f, attr):
"Returns values for the attributes"
return getattr(self._o bj, attr)

def __getitem__(sel f, item):
"get attrs as items for use in string formatting templates"
value = getattr(self, item)
if callable(value) :
return value()
else:
return value

import time

class SomeObject:

"The object we want displayed in html"

def __init__(self):
self.id = 42
self.now = time.localtime( )
self.title = 'the title'

class SomeObjectHtmlV iew(HtmlViewAda pter):

"""
an adapter for the object, here you can fine adjust, format dates
etc.
"""

def title(self):
return self._obj.title .upper()

def now(self):
return time.strftime(' %y:%m:%d %H-%M-%S',self._obj.n ow)

view = SomeObjectHtmlV iew(SomeObject( ))

print '<a href="%(id)s">% (title)s</a> <i>%(now)s</i>' % view[color=blue][color=green][color=darkred]
>>> <a href="42">THE TITLE</a> <i>03:06:26 00-12-16</i>[/color][/color][/color]

**Thomas Güttler** · Jul 18 '05, 12:07 AM

Re: better way than: myPage += 'more html' , ...

Gobo Borz wrote:
[color=blue]
> Hi everyone,
>
> I have a python cgi program that uses print statements to write html.
> The program has grown, and for reasons I won't bore you with, I need to
> build the page in a string and "print" it at once.[/color]

Hi!

I do it like this:

def foo(mydict):
ret=[]

rows=[]
for key, value in mydict.items():
rows.append('<t r><td>%s</td><td>%s</td></tr>' % (key, value))
rows=''.join(ro ws)

ret.append('<ta ble>%s</table>' % rows)
return ''.join(ret)

I try to keep the start-tag and the end-tag in one string.
This keeps the code from becomming ugly.

thomas

**François Pinard** · Jul 18 '05, 12:07 AM

Re: better way than: myPage += 'more html' , ...

[Max M]
[color=blue]
> I remember reading a post where I saw meassurements that showed it to be
> twice as fast. I was too lazy too google it. But here goes. [...][/color]

[Adrien Di Mascio]
[color=blue]
> I've a made a quite basic test on these methods : [...][/color]

Thanks to both! Have a good day!

--
François Pinard http://www.iro.umontreal.ca/~pinard

**Fredrik Lundh** · Jul 18 '05, 12:08 AM

Re: better way than: myPage += 'more html' , ...

Adrien Di Mascio wrote:
[color=blue]
> I've a made a quite basic test on these methods :
>
> /snip/
>
> def write_thousands _join(self, char):
> """Writes a 100000 times 'char' in a list and joins it
> """
> str_list = []
> for index in range(100000):
> str_list.append (char)
>
> return ''.join(str_lis t)[/color]

no time to repeat your tests, but

def write_thousands _join(self, char):
"""Writes a 100000 times 'char' in a list and joins it
"""
str_list = []
append = str_list.append # bind method to local variable
for index in range(100000):
append(char)

return ''.join(str_lis t)

"should" be slightly faster.

also note that the results "may" differ somewhat if you append strings
of different lengths (mostly due to different overallocation strategies;
or maybe they're not different anymore; cannot remember...)

I always use join, but that's probably because that method is more likely
to run code that I once wrote. Never trust code written by a man who
uses defines to create his own C syntax ;-)

</F>

**Chuck Spears** · Jul 18 '05, 12:08 AM

Re: better way than: myPage += 'more html' , ...

I have a question with regards to the sprintf style of replacing
strings. I have a table in my HTML with a 50% width specifier. How
can i get the formatter to ignore it. For example in the example
below how can i code the 50% to be ignored?

keep the "%s 50% %s" % ("a","b")

better way than: myPage += 'more html' , ...

better way than: myPage += 'more html' , ...

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment