Hi, I'm new to boost / generic programming and I'm trying to understand how enable_if works because I don't like using things I don't understand. I made a simple example which I thought would have the same behavior as using enable_if but doesn't. I've attached the test could someone take a look and explain why enable_if works and the other doesn't. Thanks begin 666 main.cpp M(VEN8VQU9&4@/&)O;W-T+W5T:6QI='DO96YA8FQE7VEF+FAP<#X-"B-I;F-L M=61E(#QI;W-T<F5A;3X-"@T*;F%M97-P86-E(%1E<W1"<F]K96X-"GL-"@ET M96UP;&%T93P@8VQA<W,@5" ^#0H)<W1R=6-T(%1E<W14<F%I= T*"7L-"@E] M.PT*#0H)=&5M<&QA=&4\/@T*"7-T<G5C="!497-T5')A:70\:6YT/@T*"7L- M"@D)='EP961E9B!I;G0@96YA8FQE7W1Y<&4[#0H)?3L-"@T*"71E;7!L871E M/"!C;&%S<R!4+"!C;&%S<R!%;F%B;&4@/2!V;VED(#X-"@ES=')U8W0@16YA M8FQE5&5S= T*"7L-"@D)16YA8FQE5&5S="@I#0H)"7L-"@D)"7-T9#HZ8V]U M=" \/" B1V5N97)I8R!%;F%B;&4@5&5S="!C;VYS=')U8W1E9"(@/#P@<W1D M.CIE;F1L.PT*"0E]#0H)?3L-"@T*"71E;7!L871E/"!C;&%S<R!4(#X-"@ES M=')U8W0@16YA8FQE5&5S=#P@5"P@='EP96YA;64@5&5S=%1R86ET/%0^.CIE M;F%B;&5?='EP92 ^#0H)>PT*"0E%;F%B;&5497-T*"D-"@D)>PT*"0D)<W1D M.CIC;W5T(#P\(")3<&5C:6%L:7IE9"!%;F%B;&4@5&5S="!C;VYS=')U8W1E M9"(@/#P@<W1D.CIE;F1L.PT*"0E]#0H)?3L-"GT-"@T*;F%M97-P86-E(%1E M<W17;W)K:6YG#0I[#0H)=&5M<&QA=&4\(&-L87-S(%0@/@T*"7-T<G5C="!I M<U]I;G0-"@E[#0H)"7-T871I8R!C;VYS="!B;V]L('9A;'5E(#T@9F%L<V4[ M#0H)?3L-"@T*"71E;7!L871E/#X-"@ES=')U8W0@:7-?:6YT/&EN=#X-"@E[ M#0H)"7-T871I8R!C;VYS="!B;V]L('9A;'5E(#T@=')U93L-"@E].PT*#0H) M=&5M<&QA=&4\(&-L87-S(%0L(&-L87-S($5N86)L92 ]('9O:60@/@T*"7-T M<G5C="!%;F%B;&5497-T#0H)>PT*"0E%;F%B;&5497-T*"D-"@D)>PT*"0D) M<W1D.CIC;W5T(#P\(")'96YE<FEC($5N86)L92!497-T(&-O;G-T<G5C=&5D M(B \/"!S=&0Z.F5N9&P[#0H)"7T-"@E].PT*#0H)=&5M<&QA=&4\(&-L87-S M(%0@/@T*"7-T<G5C="!%;F%B;&5497-T/"!4+"!T>7!E;F%M92!B;V]S=#HZ M96YA8FQE7VEF/&ES7VEN=#Q4/B ^.CIT>7!E(#X-"@E[#0H)"45N86)L951E M<W0H*0T*"0E[#0H)"0ES=&0Z.F-O=70@/#P@(E-P96-I86QI>F5D($5N86)L M92!497-T(&-O;G-T<G5C=&5D(B \/"!S=&0Z.F5N9&P[#0H)"7T-"@E].PT* M?0T*#0II;G0@;6%I;BAV;VED*0T*>PT*"7-T9#HZ8V]U=" \/" B/3T](%1E M<W0@5V]R:VEN9R ]/3TB(#P\('-T9#HZ96YD;#L-"@ES=&0Z.F-O=70@/#P@ M(D9L;V%T.B(@/#P@<W1D.CIE;F1L.PT*"7M497-T5V]R:VEN9SHZ16YA8FQE M5&5S=#QF;&]A=#X@=&5M<#M]#0H-"@ES=&0Z.F-O=70@/#P@(DEN=#HB(#P\ M('-T9#HZ96YD;#L-"@E[5&5S=%=O<FMI;F<Z.D5N86)L951E<W0\:6YT/B!T M96UP.WT-"@T*"7-T9#HZ8V]U=" \/" B0F]O;#HB(#P\('-T9#HZ96YD;#L- M"@E[5&5S=%=O<FMI;F<Z.D5N86)L951E<W0\8F]O;#X@=&5M<#M]#0H-"@ES M=&0Z.F-O=70@/#P@(CT]/2!497-T($)R;VME;B ]/3TB(#P\('-T9#HZ96YD M;#L-"@ES=&0Z.F-O=70@/#P@(D9L;V%T.B(@/#P@<W1D.CIE;F1L.PT*"7M4 M97-T0G)O:V5N.CI%;F%B;&5497-T/&9L;V%T/B!T96UP.WT-"@T*"7-T9#HZ M8V]U=" \/" B26YT.B(@/#P@<W1D.CIE;F1L.PT*"7M497-T0G)O:V5N.CI% M;F%B;&5497-T/&EN=#X@=&5M<#M]#0H-"@ES=&0Z.F-O=70@/#P@(D)O;VPZ M(B \/"!S=&0Z.F5N9&P[#0H)>U1E<W1"<F]K96XZ.D5N86)L951E<W0\8F]O :;#X@=&5M<#M]#0H-"@ER971U<FX@,#L-"GT` ` end