question on buffer-file-coding-system

Charles G Waldman writes: > I just found that hexl is broken if you build XEmacs without > FILE_CODING turned on - it attempts to take the value of the variable > buffer-file-coding-system which is not defined if FILE_CODING is not > enabled. > [...] > What is the right way to handle this? Check for boundp in Lisp code, > or make sure the variable is defined even if FILE_CODING is not > enabled? Or some other approach? Check whether the variable is bound if that is all that the program needs to know. But if a more general question is being asked such as 'is MULE support available?', then use a broader check like (featurep 'mule). Some programs will set variables unconditionally so you can't rely on (boundp 'buffer-file-coding-system) meaning MULE or file-coding support is available.