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Dima and all,
I'd agree that an 'If then else' and 'For/while
next loops' would be very useful - that seems to be turning AFL into a macro
language and would be useful.
Cheers,
Geoff
<BLOCKQUOTE
>
----- Original Message -----
<DIV
>From:
Dima
Rasnitsyn
To: <A
href=""
title=amibroker@xxxxxxxxxxx>amibroker@xxxxxxxxxxx
Sent: Sunday, January 21, 2001 2:56
PM
Subject: RE: [amibroker] AFL
comments
<FONT color=navy face=Arial
size=2><SPAN
>Hello
Tomasz!
<FONT color=navy face=Arial
size=2><SPAN
>
<FONT color=navy face=Arial
size=2><SPAN
>Thank
you very much for your response.
<FONT color=navy face=Arial
size=2><SPAN
>
<FONT color=navy face=Arial
size=2><SPAN
>As a
software engineer (yes, you are right), I would like to ask for three more
enhancements. I’m not sure whether they are valuable for the majority of
AmiBroker customers – long-term stock investors, but they would be definitely
beneficial for short-term and commodity traders, especially for those using
complicated custom indicators and/or trading
systems.
<FONT color=navy face=Arial
size=2><SPAN
>
<P class=MsoNormal
><SPAN
class=EmailStyle18><SPAN
>1)<FONT
face="Times New Roman" size=1><SPAN
>
<FONT
color=navy face=Arial size=2><SPAN
>It
would be nice if the functions like ref(), valuewhen(), etc. with an argument
of type CONST will accept a NUMBER, so it will be possible to
do:
<FONT
color=navy face=Arial size=2><SPAN
>N =
MIN (a, b);
<FONT
color=navy face=Arial size=2><SPAN
>prevOpen
= ref (open, N);
<FONT
color=navy face=Arial size=2><SPAN
>
<P class=MsoNormal
><SPAN
class=EmailStyle18><SPAN
>2)<FONT
face="Times New Roman" size=1><SPAN
>
<FONT
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><SPAN
> For/while loops and IF-THEN-ELSE
constructs would be useful as well. The last would save complicated
multi-level IIF constructs.
<FONT
color=navy face=Arial size=2><SPAN
>
<P class=MsoNormal
><SPAN
class=EmailStyle18><SPAN
>3)<FONT
face="Times New Roman" size=1><SPAN
>
<FONT
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>Functions
(AFL file name where the function is defined), or simple ‘include’
construction can help to reduce code size and complexity for sophisticated
custom indicators and/or trading systems.
<FONT color=navy face=Arial
size=2><SPAN
>
<FONT color=navy face=Arial
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>
<FONT color=navy face=Arial
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>As for
my 47Kb formula, I think about 80% of this code is targeted to workaroundthe
current limitations of AFL listed in the message #859 (<A
href="">http://www.egroups.com/message/amibroker/859).
It’s my system for trading NYBOT Sugar (I’ve not tested it onother
commodities yet), and the indicators showing graphically the account balance
and results of each trade. BTW, it would be very useful if the automatic
analysis tool will graph the account value and trade results.
<FONT color=navy face=Arial
size=2><SPAN
>I can
send this code directly to you if you are curious to see how a mad software
engineer can write 47K code in 4-th generation scripting language to implement
a trading system based on 2 simple price formations <SPAN
class=EmailStyle18><SPAN
><SPAN
>J<SPAN
class=EmailStyle18><SPAN
>
<FONT color=navy face=Arial
size=2><SPAN
>
<FONT color=navy face=Arial
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>Thank
you,
<FONT color=navy face=Arial
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>Dima
<FONT color=navy face=Arial
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>
<FONT color=black face=Tahoma
size=2><SPAN
>-----Original
Message-----From: AmiBroker
Support [mailto:support@xxxx]<SPAN
>Sent: Saturday, January 20, 2001 6:05
AMTo:
amibroker@xxxxxxxxxxx<SPAN
>Subject: Re: [amibroker] AFL
comments
<FONT face="Times NewRoman"
size=3>
<FONT color=black
face="Courier New" size=2><SPAN
>Hello
Dima,<SPAN
>You
must be a software developer, Dima! Your requests are so
detailed!I am glad and thankful that you point out all these
things.> I'd like to request a few minor enhancements
to AFL interpreter.>> 1) The AFL buffers (in
Guru Comments, indicator builder, etc.) are> limited to about
32Kb [AFL code for my trading system is currently 47K].> Once
AFL code is larger, it becomes impossible to edit it in the window
(but> still possible to load file). It'd be great if you can
make this buffer> *unlimited*Wow! 47K formula
- that sounds truly interesting. Maybe you will uncover some
secretsabout this one?As for the limit I can
enlarge it easily to 64K but then limitation of Windows
95/98comes up:"Windows 95 implements some window
management features in 16 bits. The use of 16 bits imposes some restrictions
on parameters infunctions and messages and places limits on
internal storage. In some cases, Windows 95 provides features that can beused
to avoidthese restrictions and limitations. For example, the
standard edit control is limited to somewhat less than 64 kilobytes (K)
oftext" - taken from Microsoft Developer
NetworkThere are of course no such limitations on Windows
NT/2000 so this is not an issue for these platforms.Or... I
can switch to so-called "Rich-edit" controls that do not have such limitation
(but are slower...)>> 2) Subsequent
comments are not recognized, i.e. if I have> /*
comment one */> /* comment two */>
or> a = b; // comment one> /* comment two
*/> I get an error message pointing to the leading slash of
the> second commentThis one should be fixed
long time ago :-(> 3) result of Boolean (or any other)
operation including an array which> value is {EMPTY} for
particular date is {EMPTY}. I think {EMPTY} should be>
considered as 0. Example:> sell = exitLongPosition OR
enterShortPosition;> If my first trade for the time period is
Long, sell will have> {EMPTY} value until my first short
trade. 1 in exitLongPosition will be> ignored because of
{EMPTY} value of enterShortPosition.I guess you are right
(but for boolean operations only). Why not for all
operations?Simply because {EMPTY} is used to mark that thereare
no valid datafor given bar. For example moving average valueis
NOT available for the first<range> number of bars. So if
you base your other calculations on the resultsof MA you should
not include these invalid data. AFL engine detects {EMPTY}values
and skips them so nested functions/operators work only on valid
data.Best regards,Tomasz
Janeczko===============AmiBroker - the comprehensive
share manager.<A
href="">http://www.amibroker.com<FONT
color=black><BR
><BR
><FONT
color=black><SPAN
>
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