Dynamic local variables

[tom234]

(03-13-2015 07:59 PM)Han Wrote:  Here's an example of how to create dynamic local variables:

Code:

locvars:={};
locname:={};

NEWLOC();
LSTO();
LRCL();
LSTON();
LRCLN();

EXPORT DYNLOC()
BEGIN
  // an example
  local mylocal;

  mylocal:=1;
  NEWLOC("cool",0);
  LSTO("cool",-5);
  NEWLOC("alist",1);
  LSTO("alist",{1,2,3});

  mylocal:=LRCL("cool")*3;
  LRCL("alist")*mylocal+LRCLN("alist",1);
END;

// name is a string
// vtype = 0 --> atomic; 
NEWLOC(name,vtype)
BEGIN
  local j;

  j:=POS(locname,name); 

  if vtype then
    locvars(j):={0};
  else
    locvars(j):=0;
  end;
  locname(j):=name; 
END;

// name is a string
// val is the value to store
// n is the index (0 if atomic) 
LSTON(name,val,n)
BEGIN
  local j;

  j:=POS(locname,name);
  if j then
    if n then
      if n>size(locvars(j)) then
        MSGBOX("Invalid index: " + name + "(" + n + ")");
        kill;
      end;
      locvars(j,n):=val;
    else
      locvars(j):=val;
    end;
  else
    MSGBOX("Error: no such local var (" + name + ")");
    kill;
  end;
END;

// name is a string
// n is the index (0 if atomic)
LRCLN(name,n)
BEGIN
  local j;

  j:=POS(locname,name);
  if j then
    if n then
      if n>size(locvars(j)) then
        MSGBOX("Invalid index " + name + "(" + n + ")");
        kill;
      end;
      return(locvars(j,n));
    else
      return(locvars(j));
    end;
  else
    MSGBOX("Error: no such local var (" + name + ")");
    kill;
  end;
END;

LSTO(name,val)
BEGIN
  local j;

  j:=POS(locname,name);
  if j then
    locvars(j):=val;
  else
    MSGBOX("Error: no such local var (" + name + ")");
    kill;
  end;
END;

LRCL(name)
BEGIN
  local j;

  j:=POS(locname,name);
  if j then
    return(locvars(j));
  else
    MSGBOX("Error: no such local var (" + name + ")");
    kill;
  end;
END;

Explanation to come a bit later; heading home from work.

(03-15-2015 07:44 PM)Han Wrote:  

(03-13-2015 07:59 PM)Han Wrote:  Here's an example of how to create dynamic local variables:

Code:

locvars:={};
locname:={};

NEWLOC();
LSTO();
LRCL();
LSTON();
LRCLN();

EXPORT DYNLOC()
BEGIN
  // an example
  local mylocal;

  mylocal:=1;
  NEWLOC("cool",0);
  LSTO("cool",-5);
  NEWLOC("alist",1);
  LSTO("alist",{1,2,3});

  mylocal:=LRCL("cool")*3;
  LRCL("alist")*mylocal+LRCLN("alist",1);
END;

// name is a string
// vtype = 0 --> atomic; 
NEWLOC(name,vtype)
BEGIN
  local j;

  j:=POS(locname,name); 

  if vtype then
    locvars(j):={0};
  else
    locvars(j):=0;
  end;
  locname(j):=name; 
END;

// name is a string
// val is the value to store
// n is the index (0 if atomic) 
LSTON(name,val,n)
BEGIN
  local j;

  j:=POS(locname,name);
  if j then
    if n then
      if n>size(locvars(j)) then
        MSGBOX("Invalid index: " + name + "(" + n + ")");
        kill;
      end;
      locvars(j,n):=val;
    else
      locvars(j):=val;
    end;
  else
    MSGBOX("Error: no such local var (" + name + ")");
    kill;
  end;
END;

// name is a string
// n is the index (0 if atomic)
LRCLN(name,n)
BEGIN
  local j;

  j:=POS(locname,name);
  if j then
    if n then
      if n>size(locvars(j)) then
        MSGBOX("Invalid index " + name + "(" + n + ")");
        kill;
      end;
      return(locvars(j,n));
    else
      return(locvars(j));
    end;
  else
    MSGBOX("Error: no such local var (" + name + ")");
    kill;
  end;
END;

LSTO(name,val)
BEGIN
  local j;

  j:=POS(locname,name);
  if j then
    locvars(j):=val;
  else
    MSGBOX("Error: no such local var (" + name + ")");
    kill;
  end;
END;

LRCL(name)
BEGIN
  local j;

  j:=POS(locname,name);
  if j then
    return(locvars(j));
  else
    MSGBOX("Error: no such local var (" + name + ")");
    kill;
  end;
END;

Explanation to come a bit later; heading home from work.

And for the explanation:

Normally, one must declare all variables prior to their use. In this template, one only has to declare two generic container variables: localvars and localname. The variable localvars stores the values of the variables whereas localname stores their ascii names. We use localname as a lookup table to determine the index to use within localvars get the corresponding value.

NEWLOC("varname", type) -- creates a variable with name "varname" and initializes it to either 0 or {0} depending on whether type is 0 or non-zero (atomic versus composite variable). Thus, to create a list, one could do: NEWLOC("mylist",1). If that variable already exists, then it is reset. If not, then it is created as a new entry in both localvars and localname.

LSTO("varname",value) -- stores a value into "varname"

LSTON("varname", value, index) -- stores a value into the n-th position in a composite variable "varname". For example, LSTON("mylist",-3,5) is equivalent to mylist(5):=-3

LRCL and LRCLN behave similarly but recalls the value stored in the local variables.

////
this does not run on HPG2 why.