Re: [boost] Re: Runtime error reporting

From: David Abrahams (abrahams_at_[hidden])
Date: 2001-03-20 19:22:23

It seems to me that assertion is inappropriate here and exceptions should be
used instead, though. Am I missing something important?

----- Original Message -----
From: "Aleksey Gurtovoy" <alexy_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Tuesday, March 20, 2001 4:30 PM
Subject: RE: [boost] Re: Runtime error reporting

> David Abrahams wrote:
> > Actually, I disagree. IMO, the stuff in assert() is very easy
> > to separate from the mainline code. Everyone must follow the rule
> > "no side-effects in assert" anyway. Adding a VERIFY() macro just
> > gives us another macro to keep track of. How does it help in any
> > substantive way?
>
> Taking Win32 API as an example, in theory almost every function call there
> can fail, and consistent checking for it really helps to detect induced
> errors (and their sources, of course). The problem with having only
classic
> 'assert'-like macro as a checking tool for such errors is that consistent
> application of "check a return value of every API function call" policy
> makes your code much more bloated and clumsy, e.g.:
>
> void clipboard::put_text(std::string const& text) {
>   HGLOBAL handle = ::GlobalAlloc( GHND, text.length() + 1 );
>   // copy text to allocated memory
>   // ..
>   // copy text to clipboard
>   bool result1 = ::OpenClipboard(0);
>   assert(result1);
>   bool result2 = ::EmptyClipboard();
>   assert(result2);
>   bool result3 = ::SetClipboardData(CF_TEXT, handle);
>   assert(result3);
>   bool result4 = ::CloseClipboard();
>   assert(result4);
> }
>
> vs.
>
> void clipboard::put_text(std::string const& text) {
>   HGLOBAL handle = ::GlobalAlloc( GHND, text.length() + 1 );
>   // copy text to allocated memory
>   // ..
>   // copy text to clipboard
>   sys_verify(::OpenClipboard(0));
>   sys_verify(::EmptyClipboard());
>   sys_verify(::SetClipboardData(CF_TEXT, handle));
>   sys_verify(::CloseClipboard());
> }
>
> You can beautify the first version a little by rearranging the code like
> this:
>
>   { bool result = ::OpenClipboard(0); assert(result); }
>   { bool result = ::EmptyClipboard(); assert(result); }
>   // etc.
>
> but IMO 'sys_verify' version is still much more appealing here.
>
> Aleksey
>
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