New Demo Program - GUI interface to REPL + Watch list for variables and expressions

DemoPrograms/Demo_Python_REPL_Variable_Watches_In_GUI.py

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+import subprocess
+import sys
+import ast
+import copy
+import PySimpleGUI as sg
+
+"""
+    Python repl with a "watch list"
+    This Demo Program was created as an answer to a Reddit question.
+    The idea is to build a Python interpreter >>> prompt, accept command and execute them... and
+    to also inslude a watcher feature.  The "Watched" variables or expressions are constantly updated
+    as the proram runs.
+    At the moment, the event loop runs once a second.  It could easily be shortened if that's too slow
+"""
+
+
+def convertExpr2Expression(Expr):
+        Expr.lineno = 0
+        Expr.col_offset = 0
+        result = ast.Expression(Expr.value, lineno=0, col_offset = 0)
+
+        return result
+
+def exec_with_return(code):
+    code_ast = ast.parse(code)
+
+    init_ast = copy.deepcopy(code_ast)
+    init_ast.body = code_ast.body[:-1]
+
+    last_ast = copy.deepcopy(code_ast)
+    last_ast.body = code_ast.body[-1:]
+
+    exec(compile(init_ast, "<ast>", "exec"), globals())
+    if type(last_ast.body[0]) == ast.Expr:
+        return eval(compile(convertExpr2Expression(last_ast.body[0]), "<ast>", "eval"),globals())
+    else:
+        exec(compile(last_ast, "<ast>", "exec"),globals())
+
+
+def func(x=''):
+    return f'return value from func()={x}'
+
+
+def main():
+    def InVar(key1, key2):
+        row1 = [sg.T(''), sg.I(key=key1, size=(18,1)), sg.I(key=key1+'CHANGED_', size=(18,1)),                sg.T('  '),
+                sg.T(''), sg.I(key=key2, size=(18, 1)), sg.I(key=key2 + 'CHANGED_', size=(18, 1))]
+        return row1
+
+    variables_frame = [ InVar('_VAR1_', '_VAR2_'),
+                        InVar('_VAR3_', '_VAR4_'),
+                        InVar('_VAR5_', '_VAR6_'),]
+
+    interactive_frame = [[sg.T('>>> '), sg.In(size=(70,1), key='_INTERACTIVE_'), sg.B('Go', bind_return_key=True, visible=False)],
+                [sg.Output(size=(70,8))],]
+
+    layout = [
+                [sg.Frame('Variables or Expressions to Watch', variables_frame)],
+                [sg.Frame('Interactive REPL', interactive_frame)],
+                [sg.Button('Exit')]]
+
+    window = sg.Window('Realtime REPL Command Output + Watches', layout).Finalize()
+    window.Element('_INTERACTIVE_').SetFocus()
+    event_loop(window)
+
+
+def event_loop(window):
+    var = 0
+    while True:             # Event Loop
+        event, values = window.Read(timeout=1000)
+        if event in (None, 'Exit'):
+            break
+        cmd = values['_INTERACTIVE_']
+        if event == 'Run':
+            runCommand(cmd=cmd, window=window)
+        elif event == 'Go':
+            window.Element('_INTERACTIVE_').Update('')
+            out=''
+            print(">>> ", cmd)
+            try:
+                print(exec_with_return(cmd))
+            except Exception as e:
+                print(f'Exception on output {e}')
+        # -------------------- Process the "watch list" ------------------
+        for i in range(1, 6):
+            key = f'_VAR{i}_'
+            out_key = f'_VAR{i}_CHANGED_'
+            if window.Element(key):
+                if values[key]:
+                    try:
+                        window.Element(out_key).Update(eval(values[key]))
+                    except:
+                        window.Element(out_key).Update('')
+        var += 1
+    window.Close()
+
+
+def runCommand(cmd, timeout=None, window=None):
+    """ run shell command
+	@param cmd: command to execute
+	@param timeout: timeout for command execution
+	@param window: the PySimpleGUI window that the output is going to (needed to do refresh on)
+	@return: (return code from command, command output)
+	"""
+    p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+    output = ''
+    for line in p.stdout:
+        line = line.decode(errors='replace' if (sys.version_info) < (3, 5) else 'backslashreplace').rstrip()
+        output += line
+        print(line)
+        window.Refresh() if window else None        # yes, a 1-line if, so shoot me
+
+    retval = p.wait(timeout)
+    return (retval, output)
+
+main()
+print('Exited program....')