An exception is an occurrence in an application process that requires deviation from the program's normal flow.

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64
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8answers
14k views

Defensive Programming vs Exception Handling?

I'm working through the book "Head First Python" (it's my language to learn this year) and I got to a section where they argue about two code techniques: Defensive coding vs Exception handling. Here ...
37
votes
8answers
16k views

Are exceptions as control flow considered a serious antipattern? If so, Why?

Back in the late 90's I worked quite a bit with a code base that used exceptions as flow control. It implemented a finite state machine to drive telephony applications. Lately I am reminded of those ...
113
votes
26answers
24k views

Are null references really a bad thing?

I've heard it said that the inclusion of null references in programming languages is the "billion dollar mistake". But why? Sure, they can cause NullReferenceExceptions, but so what? Any element of ...
18
votes
6answers
7k views

Efficient try / catch block usage?

Should catch blocks be used for writing logic i.e. handle flow control etc? Or just for throwing exceptions? Does it effect efficiency or maintainability of code? What are the side effects (if there ...
71
votes
12answers
8k views

I've been told that Exceptions should only be used in exceptional cases. How do I know if my case is exceptional?

My specific case here is that the user can pass in a string into the application, the application parses it and assigns it to structured objects. Sometimes the user may type in something invalid. ...
25
votes
4answers
2k views

Using assertions versus throwing exceptions?

Often when I write a functions I want to make sure the inputs to it are valid in order to detect such errors as early as possible (I believe these are called preconditions). When a precondition fails, ...
36
votes
11answers
19k views

Is catching general exceptions really a bad thing?

I typically agree with most code analysis warnings, and I try to adhere to them. However, I'm having a harder time with this one: CA1031: Do not catch general exception types I understand the ...
10
votes
4answers
1k views

Is rethrowing an exception leaking an abstraction?

I have an interface method that states in documentation it will throw a specific type of exception. An implementation of that method uses something that throws an exception. The internal exception ...
187
votes
9answers
14k views

Why do many exception messages not contain useful details?

It seems there is a certain amount of agreement that exception messages should contain useful details. Why is it that many common exceptions from system components do not contain useful details? A ...
93
votes
8answers
18k views

Exceptions: Why throw early? Why catch late?

There are many well-known best practices about exception handling in isolation. I know the "do's and don'ts" well enough, but things get complicated when it comes to best practices or patterns in ...
14
votes
9answers
11k views

if/else statements or exceptions [duplicate]

Possible Duplicate: Defensive Programming vs Exception Handling? I don't know, that this question fit better on this site, or Stack Overflow, but because my question is connected rather to ...
5
votes
5answers
3k views

How should I handle exception that *should* never be thrown? [duplicate]

What is the best way to handle errors that shouldn't ever happen? My current way to do this is to throw an exception if the 'thing that shouldn't happen' does happen, like so: /* * Restoring from a ...
51
votes
8answers
21k views

Return magic value, throw exception or return false on failure?

I sometimes end up having to write a method or property for a class library for which it is not exceptional to have no real answer, but a failure. Something cannot be determined, is not available, not ...
64
votes
7answers
67k views

Why use try … finally without a catch clause?

The classical way to program is with try ... catch. When is it appropriate to use try without catch? In Python the following appears legal and can make sense: try: #do work finally: #do ...
48
votes
12answers
29k views

Is it good practice to catch a checked exception and throw a RuntimeException?

I read some code of a colleague and found that he often catches various exceptions and then always throws a 'RuntimeException' instead. I always thought this is very bad practice. Am I wrong?
10
votes
3answers
1k views

Recommend a design pattern/approach to exposing/tolerating/recovering from system errors, Exception handling (e.g.s in Java, C++, Perl, PHP)

Can you recommend a design pattern/approach to exposing/tolerating/recovering from system errors, Exception handling (Java, C++, Perl, PHP)? Some errors need to be reported. Some errors can be ...
40
votes
11answers
6k views

Are error variables an anti-pattern or good design?

In order to handle several possible errors that shouldn't halt execution, I have an error variable that clients can check and use to throw exceptions. Is this an Anti-Pattern? Is there a better way to ...
1
vote
1answer
544 views

Pros and cons of custom exceptions [duplicate]

This may be an pointless question based on opinion, style, and context but I've been racking my brain trying to decide whether or not to make use of custom exceptions and would love to hear some pros ...
69
votes
5answers
7k views

How to write a good exception message

I'm currently doing a code review and one of the things I'm noticing are the number of exceptions where the exception message just seems to reiterate where the exception occurred. e.g. throw new ...
36
votes
4answers
4k views

Python Forgiveness vs. Permission and Duck Typing

In Python, I often hear that it is better to "beg forgiveness" (exception catching) instead of "ask permission" (type/condition checking). In regards to enforcing duck typing in Python, is this try: ...
26
votes
5answers
4k views

How to deal with checked exceptions that cannot ever be thrown

Example: foobar = new InputStreamReader(p.getInputStream(), "ISO-8859-1"); Since the encoding is hardcoded and correct, the constructor will never throw the UnsupportedEncodingException declared in ...
43
votes
20answers
12k views

Is it ever ok to have an empty catch statement?

I thought about it and could not come up with an example. Why would somebody want to catch an exception and do nothing about it? Can you give an example? Maybe it is just something that should never ...
17
votes
8answers
3k views

Error handling - Should a program fail on errors or silently ignore them

I'm writing a simple little program to transmit MIDI over a network. I know that the program will encounter transmission problems and / or other exception situations that I won't be able to predict. ...
10
votes
7answers
3k views

Is throwing an exception from a property bad form?

I've always been of the mindset that properties (ie, their set/get operations) should be fast/immediate and failure-free. You should never have to try/catch around getting or setting a property. But ...
9
votes
2answers
386 views

Use an else after exception (or not)

Consider this bit of code: if (x == 1) { throw "no good; aborting" ; } [... more code ...] Now consider this code: if (x == 1) { throw "no good; aborting" ; } else { [... more code ...] } ...
5
votes
2answers
554 views

Exception versus return code in DAO pattern

After reading a lot about the abusive use of exceptions in Java and how you should let an exception bubble up through the different layers of an application, I've come to a point where I don't know ...
40
votes
11answers
15k views

Are there any real-world cases for C++ without exceptions? [closed]

In When to use C over C++, and C++ over C? there is a statement wrt. to code size / C++ exceptions: Jerry answers (among other points): (...) it tends to be more difficult to produce truly tiny ...
44
votes
7answers
22k views

Why is there no 'finally' construct in C++?

Exception handling in C++ is limited to try/throw/catch. Unlike Object Pascal, Java, C# and Python, even in C++ 11, the finally construct has not been implemented. I have seen an awful lot of C++ ...
24
votes
4answers
13k views

Why shouldn't a method throw multiple types of checked exceptions?

We use SonarQube to analyse our Java code and it has this rule (set to critical): Public methods should throw at most one checked exception Using checked exceptions forces method callers to ...
52
votes
9answers
6k views

Throw exception or let code fail

I am wondering if there are any pros and cons against this style: private void LoadMaterial(string name) { if (_Materials.ContainsKey(name)) { throw new ArgumentException("The ...
25
votes
7answers
2k views

Should a C++ program catch all exceptions and prevent exceptions from bubbling up past main()?

I was once advised that a C++ program should ultimately catch all exceptions. The reasoning given at the time was essentially that programs which allow exceptions to bubble up outside of main() enter ...
1
vote
2answers
1k views

Exception hierarchy design

In my company we are building a webapp containing serveral central services that we design ourselves and then specify as interfaces. I.e. the interfaces are application specific and they are then ...
12
votes
5answers
2k views

Do you throw an argumentexception or argumentnullexception from private methods?

I was just reviewing some code I wrote a while back, and can see that I have a couple of private methods that throw argumentnullexceptions and/or argumentexceptions if there are issues with the ...
21
votes
2answers
1k views

Who designed exceptions?

Where did exceptions and exception handling come from? I like how .NET uses it, I like how C++ supports it (but libraries unfortunately use return code or is written in C instead). I know its pretty ...
8
votes
6answers
2k views

Do you handle Out-Of-Memory conditions?

What do you do when malloc returns 0 or new throws exception? Just halt or try to survive OOM condition/save the user's work?
7
votes
6answers
2k views

If the model is validating the data, shouldn't it throw exceptions on bad input?

Reading this SO question it seems that throwing exceptions for validating user input is frowned upon. But who should validate this data? In my applications, all validations are done in the business ...
3
votes
1answer
153 views

What are possible/useful implementations when extending exceptions?

I have seen a lot of exceptions - custom or integrated in the language (PHP) itself that have no differences but their class name. When extending default exceptions to use within your own code, are ...
39
votes
7answers
3k views

Are there legitimate reasons for returning exception objects instead of throwing them?

This question is intended to apply to any OO programming language that supports exception handling; I am using C# for illustrative purposes only. Exceptions are usually intended to be raised when an ...
41
votes
10answers
5k views

Why are exceptions considered better than explicit error testing? [duplicate]

Possible Duplicate: Defensive Programming vs Exception Handling? if/else statements or exceptions I often come across heated blog posts where the author uses the argument: "exceptions vs ...
45
votes
14answers
30k views

Is using nested try-catch blocks an anti-pattern?

Is this an antipattern? It is an acceptable practice? try { //do something } catch (Exception e) { try { //do something in the same line, but being less ambitious ...
35
votes
6answers
11k views

Workaround for Java checked exceptions

I appreciate a lot the new Java 8 features about lambdas and default methods interfaces. Yet, I still get bored with checked exceptions. For instance, if I just want to list all the visible fields of ...
19
votes
9answers
2k views

How to teach Exception Handling for New Programmers? [closed]

How do you go about teaching Exception Handling to Programmers. All other things are taught easily - Data Structures, ASP.NET, WinForms, WPF, WCF - you name it, everything can be taught easily. With ...
17
votes
2answers
1k views

What is a 'good number' of exceptions to implement for my library?

I've always wondered how many different exception classes I should implement and throw for various pieces of my software. My particular development is usually C++/C#/Java related, but I believe this ...
23
votes
11answers
6k views

Is the 'finally' portion of a 'try … catch … finally' construct even necessary?

Some languages (such as C++ and early versions of PHP) don't support the finally part of a try ... catch ... finally construct. Is finally ever necessary? Because the code in it always runs, why ...
39
votes
12answers
3k views

Why are errors named as “Exception” but not as “Error” in programming languages?

I've been thinking about that for quite a while actually. I am not a native english speaker myself but still I have years of programming experience and I always asked me this. Why is it named as ...
26
votes
5answers
2k views

Is use of finally clause for doing work after return bad style/dangerous?

As part of writing an Iterator, I found myself writing the following piece of code (stripping error handling) public T next() { try { return next; } finally { next = fetcher.fetchNext(...
20
votes
7answers
5k views

Maybe monad vs exceptions

I wonder what are the advantages of Maybe monad over exceptions? It looks like Maybe is just explicit (and rather space-consuming) way of try..catch syntax. update Please note that I'm intentionally ...
14
votes
4answers
16k views

Throwing an exception inside finally

Static code analyzers like Fortify "complain" when an exception might be thrown inside a finally block, saying that Using a throw statement inside a finally block breaks the logical progression ...
41
votes
8answers
4k views

Should I throw an exception in case of a meaningful value outside of the range or handle it myself?

I have written a struct that represents latitude/longitude coordinates. Their values range from -180 to 180 for longtitudes and 90 to -90 for lattitudes. If a user of that struct gives me a value ...
18
votes
2answers
1k views

What is the advantage of wrapping exceptions [duplicate]

It's very common in .NET for an exception to be wrapped in several layers of "outer exceptions" which give marginally more contextual data. For example, in EF if your update fails, you get exceptions ...