.net - Are nested Try/Catch blocks a bad idea? -

let's have structure so:

try   ' outer try code, can fail more generic conditions,    ' know less , might not able handle    try     ' inner try code, can fail more specific conditions,     ' know more about, , handle appropriately   catch innerex exception     ' handle inner exception   end try  catch outerex exception   ' handle outer exception end try 

i have seen opinions nesting try blocks discouraged, not find specific reasons.

is bad code? if so, why?

there circumstances they're idea, e.g. 1 try/catch whole method , inside loop want handle exception , continue processing rest of collection.

really reason if want skip bit errored , carry on, instead of unwinding stack , losing context. opening multiple files in editor example.

that said, exceptions should - exceptional. program should handle them try avoid them part of normal execution flow. they're computationally expensive in most languages (python being notable exception).

one other technique can useful catching specific exception types...

try     'some code read file  catch ex ioexception     'handle file access issues (possibly silently depending on usage) catch ex exception     ' handle other exceptions.     ' if you've got handler further up, omit catch , let      ' exception propagate     throw end try 

as pointed out gooch in comments below, use nested try/catches in our error handling routines...

    try         try             'log database         catch ex exception             'do nothing         end try          try             'log file         catch ex exception             'do nothing         end try     catch ex exception         'give , go home     end try