When should assertions stay in production code? [closed]

Assertions are comments that do not become outdated. They document which theoretical states are intended, and which states should not occur. If code is changed so states allowed change, the developer is soon informed and needs to update the assertion.

Allow me to quote Steve McConnell's Code Complete. The section on Assertions is 8.2.

Normally, you don't want users to see assertion messages in production code; assertions are primarily for use during development and maintenance. Assertions are normally compiled into the code at development time and compiled out of the code for production.

However, later in the same section, this advice is given:

For highly robust code, assert and then handle the error anyway.

I think that as long as performance is not an issue, leave the assertion in, but rather than display a message, have it write to a log file. I think that advice is also in Code Complete, but I'm not finding it right now.

Leave assertions turned on in production code, unless you have measured that the program runs significantly faster with them turned off.

if it's not worth measuring to prove it's more efficient, then it's not worth sacrificing clarity for a performance gamble." - Steve McConnell 1993

http://c2.com/cgi/wiki?ShipWithAssertionsOn