StarMirror/CppCoreGuidelines
1
0
Fork 0
mirror of https://github.com/isocpp/CppCoreGuidelines.git synced 2024-03-22 13:30:58 +08:00
Code Issues Projects Releases Wiki Activity

Followup to close #1586

Browse Source
This commit is contained in:
hsutter 2020-03-26 11:43:27 -07:00
parent 6f01c706a8
commit 1ca5545ce1
1 changed files with 13 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
CppCoreGuidelines.md
View File

@ -20271,17 +20271,20 @@ and errors (when we didn't deal correctly with semi-constructed objects consiste
##### Example, bad
// Old conventional style: many problems
class Picture
{
int mx;
int my;
char * data;
public:
// main problem: constructor does not fully construct
Picture(int x, int y)
{
mx = x,
mx = x; // also bad: assignment in constructor body rather than in member initializer
my = y;
data = nullptr;
data = nullptr; // also bad: constant initialization in constructor rather than in member initializer
}
~Picture()
@ -20289,6 +20292,7 @@ and errors (when we didn't deal correctly with semi-constructed objects consiste
Cleanup();
}
// bad: two-phase initialization
bool Init()
{
// invariant checks
@ -20298,10 +20302,11 @@ and errors (when we didn't deal correctly with semi-constructed objects consiste
if (data) {
return false;
}
data = (char*) malloc(mx*my*sizeof(int));
data = (char*) malloc(mx*my*sizeof(int)); // also bad: owning raw * and malloc
return data != nullptr;
}
// also bad: no reason to make cleanup a separate function
void Cleanup()
{
if (data) free(data);
@ -20320,11 +20325,11 @@ and errors (when we didn't deal correctly with semi-constructed objects consiste
class Picture
{
ptrdiff_t mx;
ptrdiff_t my;
int mx;
int my;
vector<char> data;
static ptrdiff_t check_size(ptrdiff_t size)
static int check_size(int size)
{
// invariant check
Expects(size > 0);
@ -20333,7 +20338,7 @@ and errors (when we didn't deal correctly with semi-constructed objects consiste
public:
// even better would be a class for a 2D Size as one single parameter
Picture(ptrdiff_t x, ptrdiff_t y)
Picture(int x, int y)
: mx(check_size(x))
, my(check_size(y))
// now we know x and y have a valid size
@ -20341,6 +20346,7 @@ and errors (when we didn't deal correctly with semi-constructed objects consiste
{
// picture is ready-to-use
}
// compiler generated dtor does the job. (also see C.21)
};