feat: sys.displayhook, fix(py): repl now sets _

Author: litlighilit

Python/intrinsics.nim

@@ -0,0 +1,15 @@
+
+import ./sysmodule/attrs
+import ./call
+import ../Objects/[
+  pyobject, exceptions,
+]
+import ../Include/internal/pycore_global_strings
+
+# ******* Unary functions *******
+proc print_expr*(value: PyObject; res: var PyObject): PyBaseErrorObject =
+  var hook: PyObject
+  retIfExc PySys_GetAttr(pyID(displayhook), hook)
+  res = call(hook, value)
+  retIfExc res
+  res = nil

Python/neval.nim

@@ -8,13 +8,14 @@ import builtindict
 import ../Objects/[pyobject, baseBundle, tupleobject, listobject, dictobject,
                    sliceobject, codeobject, frameobject, funcobject, cellobject,
                    setobject, notimplementedobject, boolobjectImpl,
-                   exceptionsImpl, methodobject,
+                   exceptionsImpl,
                    ]
 import ../Objects/abstract/[dunder, number,]
 import ../Utils/utils
 import ./[
   neval_frame,
   pyimport,
+  intrinsics,
 ]
 export pyimport, neval_frame
 
@@ -385,17 +386,10 @@ proc evalFrame*(f: PyFrameObject): PyObject =
 
             of OpCode.PrintExpr:
               let top = sPop()
-              if top.id != pyNone.id:
-                # all object should have a repr method properly initialized in typeobject.nim
-                let reprObj = top.pyType.magicMethods.repr(top)
-                if reprObj.isThrownException:
-                  handleException(reprObj)
-
-                # todo: optimization - build a cache
-                let printFunction = PyNimFuncObject(KeyError!bltinDict[newPyAscii"print"])
-                let retObj = tpMagic(NimFunc, call)(printFunction, @[reprObj])
-                if retObj.isThrownException:
-                  handleException(retObj)
+              var unused: PyObject
+              let retObj: PyBaseErrorObject = print_expr(top, unused)
+              if not retObj.isNil:
+                handleException(retObj)
 
             of OpCode.LoadBuildClass:
               sPush KeyError!bltinDict[newPyAscii"__build_class__"]

Python/sysmodule.nim

@@ -28,6 +28,7 @@ implSysModuleMethod audit(eventObj: PyStrObject, *args):
 implSysModuleMethod excepthook(exctype: PyTypeObject, value: PyBaseErrorObject, traceback):
   excepthook(exctype, value, traceback)
   pyNone
+implSysModuleMethod displayhook(x): displayhook(x)
 
 implSysModuleMethod get_int_max_str_digits(): newPyInt PySys_GetIntMaxStrDigits()
 implSysModuleMethod set_int_max_str_digits(*a, **kw):

Python/sysmodule/hooks.nim

@@ -1,7 +1,53 @@
 
-import ../../Objects/[pyobjectBase, exceptions,]
+import ../../Objects/[
+  pyobjectBase, exceptions,
+  noneobject,
+  stringobject,
+  ]
+import ../../Objects/pyobject_apis/[attrs, io]
 import ../pythonrun/pyerr_display
-
+import ../pyimport/utils
+import ../../Include/internal/pycore_global_strings
+import ../../Utils/[fileio,]
 
 proc excepthook*(exctype: PyObject, value: PyBaseErrorObject, traceback: PyObject) =
   PyErr_Display(nil, value, traceback)
+
+proc displayhook_impl*(o: PyObject): PyBaseErrorObject =
+  var builtins: PyObject
+  retIfExc PyImport_GetModule(pyId(builtins), builtins)
+  if builtins.isNil:
+    return newRuntimeError newPyAscii"lost builtins module"
+  retIfExc builtins
+
+  # Print value except if None
+  # After printing, also assign to '_'
+  # Before, set '_' to None to avoid recursion
+  if o.isPyNone: return
+  retIfExc PyObject_SetAttr(builtins, newPyAscii('_'), pyNone)
+
+  #TODO:sys.stdout
+  #TODO:encoding
+  #[
+  var outf: PyObject
+  retIfExc PySys_GetAttr(pyId(stdout), outf)
+  if outf.isPyNone:
+    return newRuntimeError newPyAscii"lost sys.stdout"
+  let res = PyFile_WriteObject(o, outf)
+  if res.ofPyUnicodeEncodeErrorObject:
+    #[/* repr(o) is not encodable to sys.stdout.encoding with
+      * sys.stdout.errors error handler (which is probably 'strict') */]#
+    retIfExc sys_displayhook_unencodable(outf, o)
+  retIfExc res
+  retIfExc PyFile_WriteObject(newPyAscii('\n'), outf, Py_PRINT_RAW)
+  ]#
+
+
+  let res = PyObject_Println(o, fileio.stdout)  
+  retIfExc res
+
+  retIfExc PyObject_SetAttr(builtins, newPyAscii('_'), o)
+
+proc displayhook*(o: PyObject): PyObject =
+  retIfExc displayhook_impl(o)
+  return pyNone