| 1 | // see also C++ investigation in ~/plg2/cfa2/mycode/string/raii/ctor-calls.cpp
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| 2 | 
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| 3 | #include <string.hfa>
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| 4 | #include <string_res.hfa>
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| 5 | 
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| 6 | /*
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| 7 | call_substrOfPart:
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| 8 |     In all cases, of both HL and LL, there is a temporary object.
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| 9 |     It represents narrowing the range, from full-string, to [1..3].
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| 10 |     The only matter to control is whether that temporary shares edits with the string from which it was created.
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| 11 |     In HL, two knobs control it, and the 
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| 12 | */
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| 13 | 
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| 14 | void calltest_HL() {
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| 15 | 
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| 16 |     #define HELPER_BODY(param) \
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| 17 |         sout | "early in helper with " | param; \
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| 18 |         param[0] = '+'; \
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| 19 |         sout | "late in helper with " | param;
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| 20 | 
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| 21 |     void helper1( string   q ) { HELPER_BODY(q) }
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| 22 |     void helper2( string & q ) { HELPER_BODY(q) }
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| 23 |     #undef HELPER_BODY
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| 24 | 
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| 25 |     string fred;
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| 26 | 
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| 27 | 
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| 28 |     sout | "===";
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| 29 |     sout | "HL: substring of part";
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| 30 | 
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| 31 |     sout | "---";
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| 32 |     // Calling a by-val function, the only way it supports, in which it gets a private logical copy.
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| 33 |     fred = "abcd";
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| 34 |     sout | "before helper with " | fred;
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| 35 |     helper1( fred(1,3) );
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| 36 |     sout | "after helper with " | fred;
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| 37 | 
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| 38 |     sout | "---";
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| 39 |     // Calling a by-ref function, sys-style, in which we want to gets its changes as side effects.
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| 40 |     fred = "abcd";
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| 41 |     sout | "before helper with " | fred;
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| 42 |     helper2( fred(1,3) );
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| 43 |     sout | "after helper with " | fred;
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| 44 | 
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| 45 |     sout | "---";
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| 46 |     // Calling a by-ref function, trans-style, in which we give it a logical copy, to prevent it from pulluting our gold one.
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| 47 |     fred = "abcd";
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| 48 |     sout | "before helper with " | fred;
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| 49 |     helper2( (string){ fred(1,3) } );
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| 50 |     sout | "after helper with " | fred;
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| 51 | 
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| 52 | 
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| 53 |     sout | "===";
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| 54 |     sout | "HL: substring of whole";
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| 55 | 
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| 56 |     sout | "---";
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| 57 |     // Calling a by-val function, the only way it supports, in which it gets a private logical copy.
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| 58 |     fred = "abcd";
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| 59 |     sout | "before helper with " | fred;
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| 60 |     helper1( fred(0,4) );
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| 61 |     sout | "after helper with " | fred;
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| 62 | 
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| 63 |     sout | "---";
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| 64 |     // Calling a by-ref function, sys-style, in which we want to gets its changes as side effects.
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| 65 |     fred = "abcd";
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| 66 |     sout | "before helper with " | fred;
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| 67 |     helper2( fred(0,4) );
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| 68 |     sout | "after helper with " | fred;
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| 69 | 
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| 70 |     sout | "---";
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| 71 |     // Calling a by-ref function, trans-style, in which we give it a logical copy, to prevent it from pulluting our gold one.
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| 72 |     fred = "abcd";
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| 73 |     sout | "before helper with " | fred;
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| 74 |     helper2( (string){ fred(0,4) } );
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| 75 |     sout | "after helper with " | fred;
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| 76 | 
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| 77 | 
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| 78 | 
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| 79 |     sout | "===";
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| 80 |     sout | "HL: whole original string";
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| 81 | 
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| 82 |     sout | "---";
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| 83 |     // Calling a by-val function, the only way it supports, in which it gets a private logical copy.
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| 84 |     fred = "abcd";
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| 85 |     sout | "before helper with " | fred;
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| 86 |     helper1( fred );
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| 87 |     sout | "after helper with " | fred;
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| 88 | 
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| 89 |     sout | "---";
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| 90 |     // Calling a by-ref function, sys-style, in which we want to gets its changes as side effects.
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| 91 |     fred = "abcd";
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| 92 |     sout | "before helper with " | fred;
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| 93 |     helper2( fred );
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| 94 |     sout | "after helper with " | fred;
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| 95 | 
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| 96 |     sout | "---";
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| 97 |     // Calling a by-ref function, trans-style, in which we give it a logical copy, to prevent it from pulluting our gold one.
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| 98 |     fred = "abcd";
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| 99 |     sout | "before helper with " | fred;
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| 100 |     helper2( (string){ fred } );
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| 101 |     sout | "after helper with " | fred;
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| 102 | }
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| 103 | 
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| 104 | void calltest_LL() {
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| 105 | 
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| 106 |     #define HELPER_BODY(param) \
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| 107 |         sout | "early in helper with " | param; \
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| 108 |         assignAt(param, 0, '+'); \
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| 109 |         sout | "late in helper with " | param;
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| 110 | 
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| 111 |     void helper1( string_res & q ) { HELPER_BODY(q) } // arg should always be a temporary constructed with COPY_VALUE
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| 112 |     void helper2( string_res & q ) { HELPER_BODY(q) } // arg can refer to whatever you want
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| 113 |     #undef HELPER_BODY
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| 114 | 
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| 115 |     /*
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| 116 |     In LL, both functions are translated to the same thing.
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| 117 |     "The only allowed call of #1" becomes respecting the restriction of the comment at helper1.
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| 118 |     A sys call of #2 is different from the only allowed call of #1.
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| 119 |     A trans call of #2 is the same as the only allowed call of #1.
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| 120 |     */
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| 121 | 
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| 122 |     string_res fred;
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| 123 | 
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| 124 |     sout | "===";
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| 125 |     sout | "LL: substring of part";
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| 126 | 
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| 127 |     sout | "---";
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| 128 |     // Calling a by-val function, the only way it supports, in which it gets a private logical copy.
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| 129 |     fred = "abcd";
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| 130 |     sout | "before helper with " | fred;
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| 131 |     helper1( (string_res){ fred, COPY_VALUE, 1, 3 } );
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| 132 |     sout | "after helper with " | fred;
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| 133 | 
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| 134 |     sout | "---";
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| 135 |     // Calling a by-ref function, sys-style, in which we want to gets its changes as side effects.
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| 136 |     fred = "abcd";
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| 137 |     sout | "before helper with " | fred;
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| 138 |     helper2( (string_res){ fred, SHARE_EDITS, 1, 3 } );
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| 139 |     sout | "after helper with " | fred;
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| 140 | 
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| 141 |     sout | "---";
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| 142 |     // Calling a by-ref function, trans-style, in which we give it a logical copy, to prevent it from pulluting our gold one.
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| 143 |     fred = "abcd";
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| 144 |     sout | "before helper with " | fred;
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| 145 |     helper2( (string_res){ fred, COPY_VALUE, 1, 3 } );
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| 146 |     sout | "after helper with " | fred;
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| 147 | 
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| 148 | 
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| 149 |     sout | "===";
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| 150 |     sout | "LL: substring of whole";
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| 151 | 
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| 152 |     sout | "---";
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| 153 |     // Calling a by-val function, the only way it supports, in which it gets a private logical copy.
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| 154 |     fred = "abcd";
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| 155 |     sout | "before helper with " | fred;
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| 156 |     helper1( (string_res){ fred, COPY_VALUE, 0, 4 } );
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| 157 |     sout | "after helper with " | fred;
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| 158 | 
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| 159 |     sout | "---";
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| 160 |     // Calling a by-ref function, sys-style, in which we want to gets its changes as side effects.
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| 161 |     fred = "abcd";
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| 162 |     sout | "before helper with " | fred;
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| 163 |     helper2( (string_res){ fred, SHARE_EDITS, 0, 4 } );
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| 164 |     sout | "after helper with " | fred;
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| 165 | 
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| 166 |     sout | "---";
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| 167 |     // Calling a by-ref function, trans-style, in which we give it a logical copy, to prevent it from pulluting our gold one.
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| 168 |     fred = "abcd";
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| 169 |     sout | "before helper with " | fred;
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| 170 |     helper2( (string_res){ fred, COPY_VALUE, 0, 4 } );
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| 171 |     sout | "after helper with " | fred;
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| 172 | 
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| 173 | 
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| 174 |     sout | "===";
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| 175 |     sout | "LL: whole original string";
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| 176 | 
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| 177 |     sout | "---";
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| 178 |     // Calling a by-val function, the only way it supports, in which it gets a private logical copy.
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| 179 |     fred = "abcd";
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| 180 |     sout | "before helper with " | fred;
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| 181 |     helper1( (string_res){ fred, COPY_VALUE } );
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| 182 |     sout | "after helper with " | fred;
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| 183 | 
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| 184 |     sout | "---";
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| 185 |     // Calling a by-ref function, sys-style, in which we want to gets its changes as side effects.
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| 186 |     fred = "abcd";
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| 187 |     sout | "before helper with " | fred;
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| 188 |     helper2( fred );
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| 189 |     sout | "after helper with " | fred;
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| 190 | 
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| 191 |     sout | "---";
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| 192 |     // Calling a by-ref function, trans-style, in which we give it a logical copy, to prevent it from pulluting our gold one.
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| 193 |     fred = "abcd";
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| 194 |     sout | "before helper with " | fred;
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| 195 |     helper2( (string_res){ fred, COPY_VALUE } );
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| 196 |     sout | "after helper with " | fred;
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| 197 | }
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| 198 | 
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| 199 | 
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| 200 | 
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| 201 | int main() {
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| 202 | 
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| 203 |     calltest_HL();
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| 204 |     calltest_LL();
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| 205 | 
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| 206 | }
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