TEDIT BOUT should replace and not insert

[rmkaplan]

A Tedit text stream tries to simulate the behavior of other streams (files, strings) as much as possible, through the :TEXTSTREAM external format. It has difference in one respect: If BOUT is defined for other streams and it is applied when the file pointer is not at the end of the stream, then the byte at the current character position is replaced. If it is applied at the end of the stream, it is added on. But Tedit's BOUT currently inserts the character in the middle rather than replacing, pushhing all later characters down and growing the file.

Tedit should also do a replace in that situation, so that a program that writes to other streams will see the same behavior if given a Tedit stream to write on.

[masinter]

i'm not convinced this is a positive thing to do. The current behavior is intentional. SEdit doesn't overwrite S-expressions when you type into it. If there are applications that rely on "insert on typein" behavior, this is a problem. Is there any application where mzking it overright rather than insert would be better?

[rmkaplan]

Sedit is not a good point of comparison. Unlike Tedit, Sedit doesn't pretend to present a stream interface to an editing session. You can PRIN1 to an Sedit window, but all that does is dirty up the image without changing the structure.

In contrast, TEdit does present a stream interface that supports the basic stream functions, except that the interface is defective in this particular way. This change would make it more likely that an application can swap in a Tedit stream in place of an ordinary file stream, even if the application is moving the fileptr around in some sophisticated way.

Tedit and Sedit are similar with respect to typein, copy selection, and copyinsert. In both cases, the behavior (replace or insert) depends on the target selection.

[masinter]

for backward cimpatibility, how about two kinds of text streams, or a stream insert/append mode or flg?