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...and finally:
5) Always check that your code works in MetaStock as intended,
preferably before posting. ;)
Correction:
Short
---8<----------
{ Variables }
SMAperiods:=14;
EnvPercent:=3;
{ Envelope signals }
Env:=EnvPercent/100;
upper:=C>(1+Env)*Mov(C,SMAperiods,S);
lower:=C<(1-Env)*Mov(C,SMAperiods,S);
{ Trade binary flag }
binary:=ValueWhen(1,upper-lower<>0,upper-lower);
{ Short trade flag }
binary<0
---8<----------
jose '-)
--- In Metastockusers@xxxxxxxxxxxxxxx, "Jose Silva" <josesilva22@xxxx>
wrote:
>
>
> Some poor MetaStock coding practices worth avoiding:
>
> 1) MetaStock's PREV function slows down processing dramatically -
> its use should be avoided wherever possible. Placing unnecessary
> PREV functions in a formula generally reflects poor programming
> skills;
>
> 2) Rather than create a zillion formulae with different hard-coded
> parameters scattered inside the formula, assign these values to
> parameters so they may be easily changed as required;
>
> 3) Always use meaningful names for variables. The code may need to
> be followed and understood by others, or worse still, Alzheimer's
> may just be around the corner;
>
> 4) Use {comments} wherever possible, for the same reasons as #3.
>
>
> Here is a recent example of code that ignores the above four points:
>
> ========================
> 3% envelope 14 MA Expert
> ========================
> ---8<--------------
> Long
>
> A:=C>1.03*Mov(C,14,S);
> B:=C<.97*Mov(C,14,S);
> D:=If(A,1,If(B,0,PREV));
> D=1
>
> Short
>
> A:=C>1.03*Mov(C,14,S);
> B:=C<.97*Mov(C,14,S);
> D:=If(A,1,If(B,0,PREV));
> D=0
>
> Symbol tab
>
> Long
>
> A:=C>1.03*Mov(C,14,S);
> B:=C<.97*Mov(C,14,S);
> D:=If(A,1,If(B,0,PREV));
> D=1 AND Ref(D,-1)=0
>
> short
>
> A:=C>1.03*Mov(C,14,S);
> B:=C<.97*Mov(C,14,S);
> D:=If(A,1,If(B,0,PREV));
> D=0 AND Ref(D,-1)=1
> ---8<--------------
>
> The code above is an example of poor coding in MetaStock, because:
>
> 1) Four (unnecessary) PREV function slows down the plotting of the
> Expert signals, and would dramatically slow down an exploration
> based on this code;
>
> 2) No parameters assigned to global variables - it would take some
> effort to change the 16 values, and there is always the risk of
> introducing errors;
>
> 3) No meaningful names assigned to variables. Try following the
> code of some of the longer formulae, and the problem becomes
> apparent;
>
> 4) No {comments} used. The author may not need them, but others
> could do with some.
>
>
> The code below plots the same signals, and:
>
> 1) Avoids PREV functions;
>
> 2) Assigns global variables to variables at the easy-to-get head of
> the formula;
>
> 3) Uses names for variables that reflect their intended use;
>
> 4 {Comments}, {Comments}, {Comments}.
>
> ===========================
> 14 SMA / 3% envelope Expert
> ===========================
>
> Highlights tab:
>
> Long
> ---8<----------
>
> { Variables }
> SMAperiods:=14;
> EnvPercent:=3;
>
> { Envelope signals }
> Env:=EnvPercent/100;
> upper:=C>(1+Env)*Mov(C,SMAperiods,S);
> lower:=C<(1-Env)*Mov(C,SMAperiods,S);
>
> { Trade binary flag }
> binary:=ValueWhen(1,upper-lower<>0,upper-lower);
>
> { Long trade flag }
> binary=1
>
> ---8<----------
>
>
> Short
> ---8<----------
>
> { Variables }
> SMAperiods:=14;
> EnvPercent:=3;
>
> { Envelope signals }
> Env:=EnvPercent/100;
> upper:=C>(1+Env)*Mov(C,SMAperiods,S);
> lower:=C<(1-Env)*Mov(C,SMAperiods,S);
>
> { Trade binary flag }
> binary:=ValueWhen(1,upper-lower<>0,upper-lower);
>
> { Short trade flag }
> binary=0
>
> ---8<----------
>
>
> Symbols tab:
>
> Long
> ---8<----------
>
> { Variables }
> SMAperiods:=14;
> EnvPercent:=3;
>
> { Envelope signals }
> Env:=EnvPercent/100;
> upper:=C>(1+Env)*Mov(C,SMAperiods,S);
> lower:=C<(1-Env)*Mov(C,SMAperiods,S);
>
> { Trade binary flag }
> binary:=ValueWhen(1,upper-lower<>0,upper-lower);
>
> { Long trade - first signal }
> long:=binary=1 AND Alert(binary<1,2);
> long
>
> ---8<----------
>
> Short
> ---8<----------
>
> { Variables }
> SMAperiods:=14;
> EnvPercent:=3;
>
> { Envelope signals }
> Env:=EnvPercent/100;
> upper:=C>(1+Env)*Mov(C,SMAperiods,S);
> lower:=C<(1-Env)*Mov(C,SMAperiods,S);
>
> { Trade binary flag }
> binary:=ValueWhen(1,upper-lower<>0,upper-lower);
>
> { Short trade - first signal }
> short:=binary<1 AND Alert(binary>0,2);
> short
>
> ---8<----------
>
> Life is so much easier with clean, annotated code... ;)
>
>
> jose '-)
> http://www.metastocktools.com
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