Forum: Cfengine Help Subject: Re: AppendIfNoLineMatching and Cfengine 3 Author: zzamboni Link to topic: https://cfengine.com/forum/read.php?3,19997,21005#msg-21005
Rob, Sorry it took me a while to respond. The reason why this works is that the normal order inside edit_line bundles is as follows: vars, classes, delete_lines, field_edits, insert_lines, replace_patterns and reports. This means that insert_lines happens before replace_patterns. If we did the insert_lines unconditionally, we would end up with a duplicated line once the replace_patterns fixes a matching line that was not already equal to the new one. Instead, I make use of the three passes that cfengine does in each bundle to skip the insert_lines the first time around, and only execute it on the second pass. By this time, if replace_patterns has already fixed the line, it will not be inserted again, because insert_lines is smart enough not to do that. On the contrary, if replace_patterns didn't find a line to fix, insert_lines will do its job and add it to the file. This is why the replace_done class is defined no matter what - in this case it is not used as an indication of the success of the promise, but rather as a flag to indicate that the replace_patterns promise has been processed at least once already. Maybe the class should be named "replace_attempted" instead of "replace_done" to better indicate its purpose. I hope this clarifies things. _______________________________________________ Help-cfengine mailing list Help-cfengine@cfengine.org https://cfengine.org/mailman/listinfo/help-cfengine
