Re: [boost] indentation algorithm for stream objects

From: Reece Dunn (msclrhd_at_[hidden])
Date: 2003-04-04 10:32:39

Larry Evans wrote:

>I disagree. The following (almost) line by line translation of your example
>to marg_ostream:

As I said, I don't know the details of the implementation, so that was a 
speculation based on how I presumed it was implemented.

>That's why I like your way; however, in the back of my mind,
>there's a feeling I started out that way (this was done years ago)
>and for some reason, after running some tests, found it better to
>do it this other way.  I think the problem was I didn't always
>know when the beginning-of-line occured; hence, I needed the
>marg_ostream to keep track of this.  I can't remember specifics
>yet.

The problem lies in what to do when reading in data from an external source 
like a file. In that instance, you have to manually scan the file for '\n' 
characters and indent then.

This is a problem with my design, one solution to which would be to provide 
a special method for string output that performs the indenting on '\n' 
characters and the default << operator for strings and characters does not 
do this.

I have made several improvements to the original code, including:

[1] added a security check for indentor::endIndent() to prevent 
m_indent.level dropping below 0

[2] added the ability for indentor::indent() to output a newline character

[3] indent() is now implemented using width() and fill() functions from 
OutputFileType, restoring their values afterwards - thanks to Larry Evans 
for the suggestion

[4] added char/wchar_t support by inheriting the character type from 
OutputFileType

-rhd-
mailto:msclrhd_at_[hidden]

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