[htmltmpl] Alternate loops

[Jonathan L. <dat...@gm...>]

Requiring that all loops be handled by iterating through lists of
hashes leads to a lot of extra work on the script writer's end, and
results in the template writer having rather inflexible data to work
with.  I'd like to propose a more flexible alternative, which ought to
be usable in addition to the current approach:

Allow the script writer to pass ordinary lists to a template.

Allow the template writer to access them using a modified version of
<TMPL_LOOP>:

<TMPL_LOOP> <!-- that's right; no loop control variable is given. -->
 <TMPL_VAR list1> <!-- list1 is an ordinary list that got passed to
the template. -->
 <TMPL_VAR list2> <!-- list2 is another such list. -->
</TMPL_LOOP>

This loop construct would display the first elements of list1 and
list2 on its first pass, the second elements of each list on its
second pass, and so on until it exhausts one of the lists (at which
point it stops).

Without a loop control variable, any variable could be used within the
loop, not just list-like variables.  So you could do something like:

 <ul>
 <TMPL_LOOP>
  <li><TMPL_VAR value_set>: <TMPL_VAR count_distribution> out of
<TMPL_VAR sum_of_counts></li>
 </TMPL_LOOP>
 </ul>

Given:
 @value_set =3D (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12);
 @count_distribution =3D (1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1);
 $sum_of_counts =3D 36;

This would produce:

 <ul>
  <li>2: 1 out of 36</li>
  <li>3: 2 out of 36</li>
  <li>4: 3 out of 36</li>
  <li>5: 4 out of 36</li>
  <li>6: 5 out of 36</li>
  <li>7: 6 out of 36</li>
  <li>8: 5 out of 36</li>
  <li>9: 4 out of 36</li>
  <li>10: 3 out of 36</li>
  <li>11: 2 out of 36</li>
  <li>12: 1 out of 36</li>
 </ul>

The only restriction would be that ordinary lists can only be used
within a TMPL_LOOP.

To me, this seems a lot more intuitive (on both ends of the design)
than the current approach, where the script writer would have to say
something like:

@loop =3D (
 {value_set =3D> 2, count_distribution =3D> 1, sum_of_counts =3D> 36 },
 {value_set =3D> 3, count_distribution =3D> 2, sum_of_counts =3D> 36 },
 {value_set =3D> 4, count_distribution =3D> 3, sum_of_counts =3D> 36 },
 {value_set =3D> 5, count_distribution =3D> 4, sum_of_counts =3D> 36 },
 {value_set =3D> 6, count_distribution =3D> 5, sum_of_counts =3D> 36 },
 {value_set =3D> 7, count_distribution =3D> 6, sum_of_counts =3D> 36 },
 {value_set =3D> 8, count_distribution =3D> 5, sum_of_counts =3D> 36 },
 {value_set =3D> 9, count_distribution =3D> 4, sum_of_counts =3D> 36 },
 {value_set =3D> 10, count_distribution =3D> 3, sum_of_counts =3D> 36 },
 {value_set =3D> 11, count_distribution =3D> 2, sum_of_counts =3D> 36 },
 {value_set =3D> 12, count_distribution =3D> 1, sum_of_counts =3D> 36 },
)

Bulky and painful.

-

You might even have it handle lists of lists, by nesting TMPL_LOOPs:

 <table>
 <TMPL_LOOP>
  <tr><TMPL_LOOP><td><TMPL_VAR count></td></TMPL_LOOP></tr>
 </TMPL_LOOP>
 </table>

and

 @count =3D ([2, 3, 4, 5, 6, 7],
           [3, 4, 5, 6, 7, 8],
           [4, 5, 6, 7, 8, 9],
           [5, 6, 7, 8, 9, 10],
           [6, 7, 8, 9, 10, 11],
           [7, 8, 9, 10, 11, 12]);

produces:

 <table>
  <tr><td>2</td><td>3</td><td>4</td><td>5</td><td>6</td><td>7</td></tr>
  <tr><td>3</td><td>4</td><td>5</td><td>6</td><td>7</td><td>8</td></tr>
  <tr><td>4</td><td>5</td><td>6</td><td>7</td><td>8</td><td>9</td></tr>
  <tr><td>5</td><td>6</td><td>7</td><td>8</td><td>9</td><td>10</td></tr>
  <tr><td>6</td><td>7</td><td>8</td><td>9</td><td>10</td><td>11</td></tr>
  <tr><td>7</td><td>8</td><td>9</td><td>10</td><td>11</td><td>12</td></tr>
 </table>

lists of lists of lists would also be possible, but the usefulness of
lists of lists is already getting close to marginal.

-

I have an idea that would allow script writers to load hashes into a
template as well; but IMHO that's not nearly as useful as loading
ordinary list variables.

--
Jonathan "Dataweaver" Lang