Why are String Formatted Queries Considered So Magical?

[Lawrence D'Oliveiro]

In message <pan.2010.06.29.09.35.18.594000 at nowhere.com>, Nobody wrote:

> On Tue, 29 Jun 2010 12:30:36 +1200, Lawrence D'Oliveiro wrote:
> 
>>> Seriously, almost every other kind of library uses a binary API. What
>>> makes databases so special that they need a string-command based API?
>> 
>> HTML is also effectively a string-based API.
> 
> HTML is a data format. The sane way to construct or manipulate HTML is via
> the DOM, not string operations.

What is this “DOM” of which you speak? I looked here 
<http://docs.python.org/library/>, but can find nothing that sounds like 
that, that is relevant to HTML.

>> And what about regular expressions?
> 
> What about them? As the saying goes:
> 
> Some people, when confronted with a problem, think
> "I know, I'll use regular expressions."
> Now they have two problems.
> 
> They have some uses, e.g. defining tokens[1]. Using them to match more
> complex constructs is error-prone ...

What if they’re NOT more complex, but they can simply contain user-entered 
data?

>> And all the functionality available through the subprocess
>> module and its predecessors?
> 
> The main reason why everyone recommends subprocess over its predecessors
> is that it allows you to bypass the shell, which is one of the most
> common sources of the type of error being discussed in this thread.

How would you deal with this, then: I wrote a script called ExtractMac, to 
convert various old Macintosh-format documents accumulated over the years 
(stored in AppleDouble form by uploading to a Netatalk server) to more 
cross-platform formats. This has a table of conversion commands to use. For 
example, the entries for PICT and TEXT Macintosh file types look like this:

    "PICT" :
      {
        "type" : "image",
        "ext" : ".png",
        "act" : "convert %(src)s %(dst)s",
      },
    "TEXT" :
      {
        "type" : "text",
        "ext" : ".txt",
        "act" : "LineEndings unix <%(src)s >%(dst)s",
      },
 
The conversion code that uses this table looks like

    Cmd = \
      (
            Act.get("act", "cp -p %(src)s %(dst)s")
        %
          {
            "src" : ShellEscape(Src),
            "dst" : ShellEscape(DstFileName),
          }
      )
    sys.stderr.write("Doing: %s\n" % Cmd)
    Status = os.system(Cmd)

How much simpler would your alternative be? I don’t think it would be 
simpler at all.