Using Python in Lazarus on Windows/Linux: what changed

Revision 0 to 1. Removed lines have a minus sign; added lines have a plus sign.

Title: Using Python in Lazarus on Windows/Linux

New		Line
1	+	# Intro
2	+
3	+	I needed to make an app, cross platform, for Windows/Linux/Mac, which embeds Python engine. I tried [[Python4Delphi]], it didn't compile and work on Linux x64 and Mac. App must use portable Python on Windows, system Python on Linux/Mac.
4	+
5	+	Update for [[Python4Delphi]]: [The commit from 21.1.2018 claims the compatibility with both Lazarus and (hopefully) Delphi Linux](https://github.com/pyscripter/python4delphi/commit/88c06f11e70d471fc5dfd3b1e7e446c09eb5ab9a)
6	+
7	+	# Results
8	+
9	+	Github repo: <https://github.com/Alexey-T/Python-for-Lazarus>
10	+
11	+	It has demo, which shows TEdit+TMemo as Python console, to input commands in Edit and show results in Memo. Special allowed first char "=" means to do "print(...)".
12	+
13	+	Screenshot on Ubuntu 14 x64:
14	+
15	+	![](/wiki-images/1/1c/Python_app_Linux.png)
16	+
17	+	Screenshot on Windows 7 x64:
18	+
19	+	![](/wiki-images/8/8b/Python_app_Windows.png)
20	+
21	+	Screenshot on macOS 10.8:
22	+
23	+	![](/wiki-images/9/93/Python_app_MacOS.png)
24	+
25	+	Repo was forked from Python4Delphi package. Compile and install the Lazarus package. You will see "Python" tab in IDE component palette. What is changed since original Python4Delphi:
26	+
27	+	- deleted all refs to units "..Delphi..", seems units aren't needed for Lazarus apps.
28	+	- modifications to PythonEngine.pas, see lines with "//AT".
29	+	- added support for macOS, for ex by replacing "\$ifdef linux" with "\$ifdef unix".
30	+
31	+	# Files on Windows
32	+
33	+	On Windows you need to copy files to app folder.
34	+
35	+	## Python 3.3
36	+
37	+	From "Sublime Text 3" installation for Windows, take Python files:
38	+
39	+	- python33.dll
40	+	- msvcr100.dll
41	+	- python33.zip
42	+	- .pyd files, copy them to subfolder DLLs
43	+
44	+	## Python 3.5 or later
45	+
46	+	You need files for another Python version: .dll, .pyd, python*.zip. Get them at official site Python.org:
47	+
48	+	- "Windows x86 embeddable zip file" for 32-bit application
49	+	- "Windows x86-64 embeddable zip file" for 64-bit application
50	+
51	+	Also you must change Lazarus component property for your Python version: DllName and/or DllPath. See the demo program, how to set them.
52	+
53	+	``` pascal
54	+	procedure TfmMain.DoPy_InitEngine;
55	+	var
56	+	S: string;
57	+	begin
58	+	S:=
59	+	{$ifdef windows} cPyLibraryWindows {$endif}
60	+	{$ifdef linux} cPyLibraryLinux {$endif}
61	+	{$ifdef darwin} cPyLibraryMac {$endif} ;
62	+	PythonEngine.DllPath:= ExtractFileDir(S);
63	+	PythonEngine.DllName:= ExtractFileName(S);
64	+	PythonEngine.LoadDll;
65	+	end;
66	+	```
67	+
68	+	## Manifest file
69	+
70	+	Manifest file (for all Python versions) should be named like "appname.exe.manifest".
71	+
72	+	``` xml
73	+	<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
74	+	<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
75	+	<noInheritable/>
76	+	<assemblyIdentity
77	+	type="win32"
78	+	name="DelphiApplication"
79	+	version="1.0.0.0"
80	+	processorArchitecture="*"/>
81	+	<dependency>
82	+	<dependentAssembly>
83	+	<assemblyIdentity type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' processorArchitecture='' publicKeyToken='6595b64144ccf1df' language='' />
84	+	</dependentAssembly>
85	+	</dependency>
86	+	<trustInfo xmlns="urn:schemas-microsoft-com:asm.v3">
87	+	<security>
88	+	<requestedPrivileges>
89	+	<requestedExecutionLevel level='asInvoker' uiAccess='false' />
90	+	</requestedPrivileges>
91	+	</security>
92	+	</trustInfo>
93	+	</assembly>
94	+	```
95	+
96	+	# Files on MacOS
97	+
98	+	macOS doesn't have preinstalled Python. User needs to install Python 3 package (demo must work with Py 3.4) from official www.python.org.
99	+
100	+	Then full path to Python library must be set in program code. It is easy to set this path, it is always the standard path like "/Library/Frameworks/Python.framework/Versions/3.5/lib/libpython3.5.dylib" (with different numbers 3.x).
101	+
102	+	# Code
103	+
104	+	## Form
105	+
106	+	Put on form:
107	+
108	+	- TPythonEngine
109	+	- TPythonInputOutput
110	+	- TCombobox (edConsole)
111	+	- TMemo (memoConsole)
112	+
113	+	Properties of PythonEngine:
114	+
115	+	- AutoLoad=False
116	+	- DllName empty
117	+	- DllPath empty
118	+	- FatalAbort=False
119	+	- InitScript="import sys; print('Python', sys.version)"
120	+	- IO=PythonInputOutput1
121	+	- PyFlags=\[pfIgnoreEnvironmentFlag\]
122	+	- UseLastKnownVersion=False
123	+
124	+	## Event handlers
125	+
126	+	- PythonEngine.OnAfterInit: must set "sys.path" for Win (remember, we use portable py for Win).
127	+
128	+	``` pascal
129	+	procedure TfmMain.PythonEngineAfterInit(Sender: TObject);
130	+	var
131	+	dir: string;
132	+	begin
133	+	{$ifdef windows}
134	+	dir:= ExtractFilePath(Application.ExeName);
135	+	Py_SetSysPath([
136	+	dir + 'DLLs',
137	+	dir + 'python33.zip'
138	+	]);
139	+	{$endif}
140	+	end;
141	+
142	+	procedure Py_SetSysPath(const Dirs: array of string);
143	+	var
144	+	Str: string;
145	+	i: Integer;
146	+	begin
147	+	Str:= '';
148	+	for i:= 0 to Length(Dirs)-1 do
149	+	Str:= Str + 'r"' + Dirs[i] + '"' + ',';
150	+	Str:= Format('sys.path = [%s]', [Str]);
151	+	GetPythonEngine.ExecString(Str);
152	+	end;
153	+	```
154	+
155	+	- PythonInputOutput.OnSendData, OnSendUniData:
156	+
157	+	``` pascal
158	+	procedure TfmMain.PythonInputOutput1SendData(Sender: TObject;
159	+	const Data: AnsiString);
160	+	begin
161	+	memoConsole.Lines.Add(Data);
162	+	end;
163	+
164	+	procedure TfmMain.PythonInputOutput1SendUniData(Sender: TObject;
165	+	const Data: UnicodeString);
166	+	begin
167	+	memoConsole.Lines.Add(Data);
168	+	end;
169	+	```
170	+
171	+	- edConsole.OnKeyPress:
172	+
173	+	``` pascal
174	+	procedure TfmMain.edConsoleKeyPress(Sender: TObject; var Key: char);
175	+	var
176	+	Str: string;
177	+	begin
178	+	if Key=#13 then
179	+	begin
180	+	Str:= edConsole.Text;
181	+
182	+	//support entering "=some cmd"
183	+	if (Str<>'') and (Str[1]='=') then
184	+	Str:= 'print('+Copy(Str, 2, MaxInt) + ')';
185	+
186	+	memoConsole.Lines.Add('>>> '+Str);
187	+	edConsole.Text:= '';
188	+	edConsole.Items.Insert(0, Str);
189	+	try
190	+	GetPythonEngine.ExecString(Str);
191	+	except
192	+	end;
193	+	end;
194	+	end;
195	+	```
196	+
197	+	- main form OnCreate:
198	+
199	+	``` pascal
200	+	const
201	+	cPyLibraryWindows = 'python33.dll';
202	+	cPyLibraryLinux = 'libpython3.4m.so.1.0';
203	+	cPyLibraryMac = '/Library/Frameworks/Python.framework/Versions/3.4/lib/libpython3.4.dylib';
204	+
205	+	procedure TfmMain.FormCreate(Sender: TObject);
206	+	var
207	+	S: string;
208	+	begin
209	+	S:=
210	+	{$ifdef windows} cPyLibraryWindows {$endif}
211	+	{$ifdef linux} cPyLibraryLinux {$endif}
212	+	{$ifdef darwin} cPyLibraryMac {$endif} ;
213	+	PythonEngine.DllPath:= ExtractFileDir(S);
214	+	PythonEngine.DllName:= ExtractFileName(S);
215	+	PythonEngine.LoadDll;
216	+	end;
217	+	```
218	+
219	+	---
220	+	From the Free Pascal wiki, page "Using Python in Lazarus on Windows/Linux", as it stood on 2020-03-04 after a change by Trev, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).
221	+	Category: Code Snippets
222	+	Category: Linux
223	+	Category: Other programming languages
224	+	Category: Python
225	+	Category: Windows

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