ListView_SetItemText is not a function, which can make someone mad
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I've run across this nasty bug in using ListView_SetItemText.
// Format64() returns a string object (which has operator const wchar*) ListView_SetItemText(items.list, i, 1, const_cast<wchar*>((const wchar*)Format64(space[i])));Runs great in debug mode, but if running actually under debugger control listview gets garbage :confused: So, lets look at the generated assembler (it always pays to at least understand asm a little) ;-) Oh, destructor for returned string object from Format64 is called before SendMessage. Blaming the compiler is generating wrong code, as temporaries must only be destructed after function call? After some thought about writing a nasty bug report I realized ListView_SetItemText is a macro.#define ListView_SetItemText(hwndLV, i, iSubItem_, pszText_) \ { LV_ITEM _ms_lvi;\ _ms_lvi.iSubItem = iSubItem_;\ _ms_lvi.pszText = pszText_;\ SNDMSG((hwndLV), LVM_SETITEMTEXT, (WPARAM)(i), (LPARAM)(LV_ITEM *)&_ms_lvi);\ }So the compiler is correct and I know once more macros are evil:)Hans
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I've run across this nasty bug in using ListView_SetItemText.
// Format64() returns a string object (which has operator const wchar*) ListView_SetItemText(items.list, i, 1, const_cast<wchar*>((const wchar*)Format64(space[i])));Runs great in debug mode, but if running actually under debugger control listview gets garbage :confused: So, lets look at the generated assembler (it always pays to at least understand asm a little) ;-) Oh, destructor for returned string object from Format64 is called before SendMessage. Blaming the compiler is generating wrong code, as temporaries must only be destructed after function call? After some thought about writing a nasty bug report I realized ListView_SetItemText is a macro.#define ListView_SetItemText(hwndLV, i, iSubItem_, pszText_) \ { LV_ITEM _ms_lvi;\ _ms_lvi.iSubItem = iSubItem_;\ _ms_lvi.pszText = pszText_;\ SNDMSG((hwndLV), LVM_SETITEMTEXT, (WPARAM)(i), (LPARAM)(LV_ITEM *)&_ms_lvi);\ }So the compiler is correct and I know once more macros are evil:)Hans
In big letters at the top of the documentaion for ListView_SetItemText is ListView_SetItemText Macro ;P
"Do you know what it's like to fall in the mud and get kicked... in the head... with an iron boot? Of course you don't, no one does. It never happens. It's a dumb question... skip it."
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In big letters at the top of the documentaion for ListView_SetItemText is ListView_SetItemText Macro ;P
"Do you know what it's like to fall in the mud and get kicked... in the head... with an iron boot? Of course you don't, no one does. It never happens. It's a dumb question... skip it."
Hi, thanks for the hint. All ListView_XXX functions are macros by the way. And most of WindowsX.h functions (well macros) are macros. So they are all possible candidates for surprises? I think we must differentiate good macros (evaluate args only once, do not scope fiddling) with evil ones (yes and for these in big red letters IS A MACRO please) :)
Hans
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Hi, thanks for the hint. All ListView_XXX functions are macros by the way. And most of WindowsX.h functions (well macros) are macros. So they are all possible candidates for surprises? I think we must differentiate good macros (evaluate args only once, do not scope fiddling) with evil ones (yes and for these in big red letters IS A MACRO please) :)
Hans
:laugh:
Hans wrote:
So they are all possible candidates for surprises?
Every time I use something new in the OS it's a candidate for a surprise!
"Do you know what it's like to fall in the mud and get kicked... in the head... with an iron boot? Of course you don't, no one does. It never happens. It's a dumb question... skip it."
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I've run across this nasty bug in using ListView_SetItemText.
// Format64() returns a string object (which has operator const wchar*) ListView_SetItemText(items.list, i, 1, const_cast<wchar*>((const wchar*)Format64(space[i])));Runs great in debug mode, but if running actually under debugger control listview gets garbage :confused: So, lets look at the generated assembler (it always pays to at least understand asm a little) ;-) Oh, destructor for returned string object from Format64 is called before SendMessage. Blaming the compiler is generating wrong code, as temporaries must only be destructed after function call? After some thought about writing a nasty bug report I realized ListView_SetItemText is a macro.#define ListView_SetItemText(hwndLV, i, iSubItem_, pszText_) \ { LV_ITEM _ms_lvi;\ _ms_lvi.iSubItem = iSubItem_;\ _ms_lvi.pszText = pszText_;\ SNDMSG((hwndLV), LVM_SETITEMTEXT, (WPARAM)(i), (LPARAM)(LV_ITEM *)&_ms_lvi);\ }So the compiler is correct and I know once more macros are evil:)Hans
That is nasty! Even though documentation says it isd a macro, this is a side effect that I think should be documented. (I shunned away from these macros most of my time anyway, now more incentive to do soo...) I wonder: would the following definition would help:
#define ListView_SetItemText(hwndLV, i, iSubItem_, pszText_) \ { LV_ITEM _ms_lvi;\ _ms_lvi.iSubItem = iSubItem_;\ (_ms_lvi.pszText = pszText_,\ SNDMSG((hwndLV), LVM_SETITEMTEXT, (WPARAM)(i), (LPARAM)(LV_ITEM *)&_ms_lvi));\ }
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