Effect of the rmargin Switch in the PWB 1.0/1.1 Editor (71415)

SUMMARY

The Programmer's WorkBench (PWB) has two switches called rmargin and wordwrap that affect behavior within the editor when typing towards the end of a line. These two switches can be used together to force line breaks as you type past a specified margin. However, the PWB documentation for versions 1.0 and 1.1 is somewhat incomplete in describing exactly how rmargin works.

The rmargin switch changed in PWB 2.0 to indicate the right margin, rather than the beginning of the word wrapping zone.

MORE INFORMATION

To use rmargin, the wordwrap switch must be set to "yes" to enable word wrapping at the right margin. With wordwrap turned on, the number specified by the rmargin switch controls the right column margin. The C version 6.0 and 6.0a "Microsoft C Reference" manual (page 83) describes the rmargin switch as follows:

Controls the right column margin used for wordwrap mode. Any character typed to the right of this margin causes a line break.

The C 6.0 and 6.0a online help for rmargin changes the wording of the second sentence above to the following:

A space typed to the right of this margin causes subsequent characters to be placed on the following line.

In reality, neither of these descriptions is entirely true. There are two ways that an automatic line break will occur:

If any space is typed after the column specified by rmargin, a forced line break will occur at that point.
If any word extends six characters past the rmargin column, a forced line break will be inserted before the word, causing the word to be moved to the next line. The documentation neglects any mention of this behavior.

These are the only two cases where PWB will force a line break. PWB does not immediately wordwrap when a character is typed past the right margin as one might expect.

In some cases, you may want to ensure that you do not have any text after a specified column. This can be done by setting rmargin to six less then the last column in which you want text to appear. A simple formula for this is:

   rmargin = last_column_to_allow_text - 6

By setting rmargin to a value as indicated by this formula, a line break will occur if a space is inserted into any of the last six columns before the column specified by last_column_to_allow_text, or a word will be moved down to the next line if it extends past last_column_to_allow_text. Thus, no characters will ever be allowed to the right of last_column_to_allow_text.