python4delphi 设置syspath

详细看demo25的代码

These techniques are demonstrated in Demo25 in the examples folder of your Python for Delphi distribution.

The old vs. the new ways.

Because Delphi 6 has custom variants, they can point to specific smart proxies for python objects.  Before Delphi 6, you could have an oleVariant pointing to a python instance, but you couldn't do the smart things like know that it was a list type etc.

The following examples assume you have a module called LoginMgr.py in the python path or in the same folder as your application  .exe that you have built in Delphi.  Note that the python file LoginMgr.py contains within it a python class called LoginMgr which has a method called somemethod.

Old way   (see my basic tutorial for more info
on the AndyDelphiPy functions.)
New way  (requires Delphi 6)

// Drop a TPythonAtomEngine onto your form
// or datamodule and name it PE
// You also need to drop a pythonDelphiVar
// component and call it pdv

uses AndyDelphiPy;

var
  obj : olevariant;
begin

AndyDelphiPy.PyExeFile('LoginMgr.py', PE);
obj  := AndyDelphiPy.PyClass('LoginMgr()', pdv, PE);
obj.somemethod()    // call the method

// Drop a TPythonAtomEngine or TPythonEngine
// onto your form or datamodule.

uses VarPyth;

var
  mymodule, obj: variant;
begin

mymodule := Import('LoginMgr');
obj := mymodule.LoginMgr();
obj.somemethod()    // call the method

Note that it it possible to slightly mix the old and new way, so that if you use the AndyDelphiPy.PyExeFile('LoginMgr.py', PE); to import the module then you can then switch to the new way, declare an obj: variant; then instantiate an instance using obj := MainModule.LoginMgr();  However you still need Delphi 6 and so you might as well just use the new way properly.

Widestrings

Declare your delphi strings widestrings if you want to get more than 255 chars back from calls to python methods that return strings. e.g.

var
   s : widestring;
begin
  s := mypythonclassinstance.somemethod() ;
showmessage(s) ;

Booleans

If your python method call returns 1 or 0 and this is supposed to be interpreted as a boolean, then cast it inside Delphi e.g.

if Boolean( mypythonclassinstance.somemethod()) then
    ....

Accessing syspath directly

Here is a function that accesses a global variable called SysModule and access the syspath directly.

This function also calls VarIsPythonSequence which tests to see if the parameter passed is a list or not.

procedure TForm1.Button2Click(Sender: TObject);
const
  LIB = 'E:\ZopeWebSite\bin\lib';
  LIBDLL = 'E:\ZopeWebSite\bin\DLLs';
var
  re : variant;
  m : variant;
begin
  memo1.lines.Add('SysModule.path is ' + SysModule.path);
  memo1.lines.Add('');
  Assert(VarIsPythonSequence(SysModule.path));
  displaySysPath(ListBox1);    

  if not Boolean(SysModule.path.Contains(LIB)) then
    SysModule.path.insert(0,LIB);
  SysModule.path.append(LIBDLL);
  memo1.lines.Add('SysModule.path now is ' + 
                   SysModule.path + #13#13);
  displaySysPath(ListBox1);    

  fixSysPath;    

  re := Import('re');
  showmessage(re);    

  m := Import('xml.dom.minidom');
  showmessage(m);    

end;    

Playing with sys paths

This is an example of how to set the python system path as seen by delphi's instance of the python interpreter (as represented by the pythonEngine component).  Note that it is imperative that you have \ as the slashed in your path as otherwise things like fred will actually be interpreted as f (whatever that escaped character is) plus 'red'. 

Technique 1

procedure TForm1.fixSysPath;
const
  LIB = 'E:\ZopeWebSitein\lib';
  LIBDLL = 'E:\ZopeWebSite\bin\DLLs';
begin    

  // this is illegal
  // SysModule.path.Clear;       

  // this will work with latest python for delphi components OK.
  //SysModule.path := NewPythonList;       

  // this is a boring but effective solution as well.
  while SysModule.path.Length > 1 do   
    SysModule.path.pop;    

  SysModule.path.append(LIBDLL);
  SysModule.path.append(LIB);
end;    

Technique 2

procedure TForm1.btnClearSyspathToJustLibClick(Sender: TObject);
var
  currdir, libdir : string;
begin
  currdir := ExtractFilePath( Application.ExeName );    

NOTE: Simply putting a window path as the currdir will ultimately fail since the paths returned by Delphi have single slashes and python needs wither unix slashes or \ slashes. See here for an algorithm to handle this.

  libdir := EnsurePathHasDoubleSlashes(libdir);    

  libdir := currdir + 'Lib';    

  SysModule.path := NewPythonList;      
  // Relies on Jan 2002 install of python for Delphi components    

  SysModule.path.append(currdir);
  SysModule.path.append(libdir);
end;    

NOTE:  See the python for delphi deployment section for a more in-depth discussion of paths.

Supplimentary utility to display the python syspath in a delphi gui control.

procedure TForm1.btnDisplaySysPathClick(Sender: TObject);
begin
  ListBox1.clear;
  displaySysPath(ListBox1);
end;

Writing a Delphi function that uses a python function to do the hard work.

Here is an example of writing a delphi utility function that takes a string, and splits it up (delimited by comma) and puts the result into a delphi list box.  We are using python split function to do the splitting - cool eh?

procedure TForm1.splitAstring(str:string; lstbox: TListBox);
var
  s, lzt : variant;
  i : integer;
begin
  s := VarPythonCreate(str);   
          // convert normal string into a python string.
  lzt := s.split(',');    

  for i := 0 to lzt.Length-1 do
    lstbox.Items.Add(lzt.GetItem(i))
end;    

Displaying the python syspath in a delphi listbox

Even though we have a pointer to a python list object (via a Delphi variant), we still have to call .GetItem(i) on a python list rather than the python syntax of lzt[i] - why? Because we are in Delphi and thus we cannot use python syntax. 

procedure TForm1.displaySysPath(lstbox: TListBox);
var
  lzt : variant;
  i : integer;
begin
  Assert(VarIsPythonSequence(SysModule.path));
  lzt := SysModule.path;
  for i := 0 to lzt.Length-1 do
    lstbox.Items.Add(lzt.GetItem(i));
  lstbox.Items.Add('----------------------------------');
end;    

Loading python base64 and minidom module and processing XML in Delphi

procedure TForm1.minidomLoadClick(Sender: TObject);
var
  m, doc, top : variant;
  s : string;
begin
  fixSysPath;
  displaySysPath(ListBox1);    

  m := Import('base64');
  showmessage(m);
  s := m.encodestring('this is some text which I am going to encode then decode again.');
  showmessage(s + #13+#13 + m.decodestring(s));    

  m := Import('xml.dom.minidom');
  doc := m.Document();
  showmessage(doc);
    

  top := doc.createElement( 'Workspace' );
  top.setAttribute('Version', '1.1 beta4');
  doc.appendChild(top);    

  s := doc.toxml();
  showmessage('doc.toxml()' + #13+#13 + s);    

end;    

Importing your own class

Ensure you have a TPythonAtomEngine or TPythonEngine onto your form or datamodule.

var
  mymodule, obj: variant;
begin    

mymodule := Import('LoginMgr');
obj := mymodule.LoginMgr();
obj.somemethod()    // call the method