Re: Should we use assert ?
On Fri, Jun 4, 2010 at 4:08 PM, Alan D. Cabrera l...@toolazydogs.comwrote: On Jun 4, 2010, at 5:10 AM, Stefan Seelmann wrote: Emmanuel Lecharny wrote: Hi guys, currently (and probably because nobody uses them, due to some Java 1.3 habits we have), we don't use asserts to do simple things like checking methods parameters (pre-conditions). Should we start using them ? I never used them before. For me assert is a bit magic because they are disabled at runtime and the assert statement isn't evaluated unless they are enabled. I prever to throw a IllegalArgumentException instead. I like asserts because they have the dual function of performing useful sanity checking when turned on and also provide implicit documentation to other developers as to what my fundamental assumptions are when I designed my code. Take for example assert Thread.holdsLock(foo) : I should be protected before you call me; This is a nice bit of code that explains my assumptions to other developers when they use/extend my code with the added benefit that it gets turned off once the code is deployed in production. Slavish use of asserts can lead to trouble; they are not a panacea. Frontline argument and state checking at the client API end should never use asserts for obvious reasons. However, performing the same kind of heavy weight checking in my internal classes where I have complete control is a bit of overkill; here asserts fit nicely. They also serve to warn the developer that they are now troweling inside the bowels of a codebase. Just my 2 cents. Alan you make very good points. I don't think we should be using asserts for API semantic checks nor going wild with it but your subtle usage to show correctness to readers of the code is very important. Seelmann's points are also solid as well. I would rather use the proper IAE in conjunction with the proper parameter checks. This falls in line with Alan's comments. I'd like to see Alan's approach while writing code to help readers understand. Plus it has value when assertion checking is enabled during tests. My 2 cents. -- Alex Karasulu My Blog :: http://www.jroller.com/akarasulu/ Apache Directory Server :: http://directory.apache.org Apache MINA :: http://mina.apache.org To set up a meeting with me: http://tungle.me/AlexKarasulu
Re: Should we use assert ?
Emmanuel Lecharny wrote: Hi guys, currently (and probably because nobody uses them, due to some Java 1.3 habits we have), we don't use asserts to do simple things like checking methods parameters (pre-conditions). Should we start using them ? I never used them before. For me assert is a bit magic because they are disabled at runtime and the assert statement isn't evaluated unless they are enabled. I prever to throw a IllegalArgumentException instead. My 2 cents, Stefan
Re: Should we use assert ?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 06/04/10 12:15, Emmanuel Lecharny wrote: Hi guys, currently (and probably because nobody uses them, due to some Java 1.3 habits we have), we don't use asserts to do simple things like checking methods parameters (pre-conditions). Should we start using them ? +1 Just make sure, that assert isn't used in places where it's shared/apacheds/... specific as an AssertationError is thrown in case. What about error messages? Do we need them here? If so it can blow up the code, just imagine something like assert ( ( value instanceof String ) || ( value instanceof byte[] ) ) : String or byte[] expected instead of + value.getClass() -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.15 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkwI7rUACgkQ2lZVCB08qHEFLQCfSzuVCIOGenudn7TExxLO/2EL 7JIAoIOuHtV2fqafEsVQLnkTjo+mFEpZ =QAuM -END PGP SIGNATURE-
Re: Should we use assert ?
On 6/4/10 2:10 PM, Stefan Seelmann wrote: Emmanuel Lecharny wrote: Hi guys, currently (and probably because nobody uses them, due to some Java 1.3 habits we have), we don't use asserts to do simple things like checking methods parameters (pre-conditions). Should we start using them ? I never used them before. For me assert is a bit magic because they are disabled at runtime and the assert statement isn't evaluated unless they are enabled. I prever to throw a IllegalArgumentException instead. It's funny because I was an heavy user of asserts when I was writing C code, and it saved me a hell lot of time. Here, we should make a distinction between using asserts and if(). Let me take an exemple. Suppose we are writing an User API, with a method taking a parameter that should not be null. Clearly, using an assert in this case is *not* valid, as it might be disabled art runtime. Now, if we are writing a method used internally, then there is no need to do a if( condition not met ) then throw new IllegalArgumentException, as it's unlikely to happen, if we have tests covering those cases. However, I won't push to much if you feel more comfortable using an if+ IllegalArgumentException. In any case, what is important is to cover the case of bad arguments being used... My 2 cents, Stefan -- Regards, Cordialement, Emmanuel Lécharny www.nextury.com
Re: Should we use assert ?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Reading http://java.sun.com/j2se/1.4.2/docs/guide/lang/assert.html#usage I have to withdraw my +1 and agree with Stefans objections On 06/04/10 14:16, Felix Knecht wrote: On 06/04/10 12:15, Emmanuel Lecharny wrote: Hi guys, currently (and probably because nobody uses them, due to some Java 1.3 habits we have), we don't use asserts to do simple things like checking methods parameters (pre-conditions). Should we start using them ? +1 Just make sure, that assert isn't used in places where it's shared/apacheds/... specific as an AssertationError is thrown in case. What about error messages? Do we need them here? If so it can blow up the code, just imagine something like assert ( ( value instanceof String ) || ( value instanceof byte[] ) ) : String or byte[] expected instead of + value.getClass() -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.15 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkwI77AACgkQ2lZVCB08qHGVDACfdHyhixrHw/gfZqQXxxiWdok7 3TEAn1o3pr6VinMwDhEt5/G/lNTbQMBK =zjLR -END PGP SIGNATURE-
Re: Should we use assert ?
On 6/4/10 2:16 PM, Felix Knecht wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 06/04/10 12:15, Emmanuel Lecharny wrote: Hi guys, currently (and probably because nobody uses them, due to some Java 1.3 habits we have), we don't use asserts to do simple things like checking methods parameters (pre-conditions). Should we start using them ? +1 Just make sure, that assert isn't used in places where it's shared/apacheds/... specific as an AssertationError is thrown in case. See my other mail about when to use asserts or not (ie, User API should not use them) What about error messages? Do we need them here? If so it can blow up the code, just imagine something like assert ( ( value instanceof String ) || ( value instanceof byte[] ) ) : String or byte[] expected instead of + value.getClass() Yes, assert must be used with a message. -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.15 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkwI7rUACgkQ2lZVCB08qHEFLQCfSzuVCIOGenudn7TExxLO/2EL 7JIAoIOuHtV2fqafEsVQLnkTjo+mFEpZ =QAuM -END PGP SIGNATURE- -- Regards, Cordialement, Emmanuel Lécharny www.nextury.com
Re: Should we use assert ?
On 6/4/10 2:21 PM, Felix Knecht wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Reading http://java.sun.com/j2se/1.4.2/docs/guide/lang/assert.html#usage I have to withdraw my +1 and agree with Stefans objections Ok, not a big deal :) -- Regards, Cordialement, Emmanuel Lécharny www.nextury.com
Re: Should we use assert ?
On Jun 4, 2010, at 5:10 AM, Stefan Seelmann wrote: Emmanuel Lecharny wrote: Hi guys, currently (and probably because nobody uses them, due to some Java 1.3 habits we have), we don't use asserts to do simple things like checking methods parameters (pre-conditions). Should we start using them ? I never used them before. For me assert is a bit magic because they are disabled at runtime and the assert statement isn't evaluated unless they are enabled. I prever to throw a IllegalArgumentException instead. I like asserts because they have the dual function of performing useful sanity checking when turned on and also provide implicit documentation to other developers as to what my fundamental assumptions are when I designed my code. Take for example assert Thread.holdsLock(foo) : I should be protected before you call me; This is a nice bit of code that explains my assumptions to other developers when they use/extend my code with the added benefit that it gets turned off once the code is deployed in production. Slavish use of asserts can lead to trouble; they are not a panacea. Frontline argument and state checking at the client API end should never use asserts for obvious reasons. However, performing the same kind of heavy weight checking in my internal classes where I have complete control is a bit of overkill; here asserts fit nicely. They also serve to warn the developer that they are now troweling inside the bowels of a codebase. Just my 2 cents. Regards, Alan
