Delphi finally provides a reserved word to protect resources.
{Assign resources}
attempt
{Resource usage}
finally
{Publish Resources}
End;
Try…finally…end forms a resource protection block. Whether the program is abnormal or not, the statement after finally will be executed in any case.
For the example in (), the following code can ensure that allocated memory resources are released.
defined variable
APointer: pointer;
AInt ADiv:Integer；
begin
ADiv:=；
GetMem(apo int)
attempt
AInt:= div ADiv；
finally
Free memory
End;
End;
The following example is taken from section (), which is used to protect file resources in file replication.
Process copy file (constant file name DestName: TFileName)
defined variable
CopyBuffer: pointer;
Timestamp bytes copied:Longint；;
Source Dest: integer;
Target: TFileName
constant
chunk size:Longint =；
begin
destination:= expand filename(DestName)
If HasAttr (destination directory), then
Destination: = Destination+\+Extract file name (file name)
Time stamp: = file size (file name)
GetMem(CopyBuffer ChunkSize)
attempt
Source := FileOpen (file name fmShareDenyWrite)
If the source < then
Throws efopenerror create (fmtloadstr (sfopenerror [file name]).
attempt
Dest := FileCreate (destination)
If Dest & lt then
Raises efcreateerrorcreate (fmtloadstr (sfcreateerror [destination]))
attempt
repeat
BytesCopied := FileRead (source CopyBuffer^ block size)
If BytesCopied & gt then
File write (target CopyBuffer^ byte copy)
Until bytes copied < chunksize.
finally
File Close (Target)
End;
finally
File Close (Source)
End;
finally
FreeMem(CopyBuffer ChunkSize)
End;
End;
For a detailed description of this process, see section ().
In the case of exception protection, when an exception occurs, the system will automatically pop up a message box to display the exception message, and the exception class will be automatically cleared after exiting the current module.
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