Softwareentwicklung in C++ - ASC

290 10. Memory – ein kleines Beispiel
5
6 #include ” s i m p l e d i s p l a y a b l e . h”
7 #include ” s i m p l e t e x t o u t p u t c o n t e x t . h”
8
9 //−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
10 /∗ A simple d i s p l a y a b l e f o r signed i n t e g e r s o f 6 4 Bits maximum length .
11 ∗ I t implements the Displayable i n t e r f a c e and i s constructed with an
12 ∗ appropriate number . When the c a l l b a c k to generate output i s c a l l e d ,
13 ∗ the i n t e g e r i s written .
14 ∗/
15 class IntDisplayable : public Displayable
16 {
17 protected :
18
19 /∗ The i n t e g e r that s h a l l be displayed as passed on in the constructor .
20 ∗/
21 int64 num ;
22
23 private :
24
25 /∗ Copy construction i s forbidden
26 ∗/
27 IntDisplayable ( const IntDisplayable & s r c ) {}
28
29 public :
30
31 /∗ Standard constructor
32 ∗ I t has to c a l l the constructor f o r the base c l a s s and s t o r e the
33 ∗ given i n t e g e r
34 ∗/
35 explicit IntDisplayable ( int64 num ) :
36 Displayable ( ) , num (num) {}
37
38 /∗ Destructor
39 ∗ Just to meet the convention
40 ∗/
41 virtual ˜ IntDisplayable ( ) { }
42
43 /∗ Nothing s p e c i a l has to be done upon r e g i s t r a t i o n
44 ∗ @param handler The handler that t h i s d i s p l a y a b l e was
45 ∗ r e g i s t e r e d with .
46 ∗/
47 virtual void d i s p l a y a b l e R e g i s t e r e d (
48 SimpleOutputHandling &handler ) {}
49
50 /∗ Writes the number to the context . This method can only work
51 ∗ with a text context .
52 ∗ @param context The output context to write to .
53 ∗/
54 virtual void writeDisplayRep ( OutputContext &context )
55 {
56 dynamic cast(context ) . write (num ) ;
57 }
58
59 } ;
60
61 #endif // s i m p l e i n t d i s p l a y a b l e h
10.2.17 TextDisplayable
Analog zur Darstellung von Ganzzahlen mittels eines besonderen Displayables
gibt es auch eine entsprechende Klasse TextDisplayable, die sich für
Strings verantwortlich fühlt: