helma.org/wiki/HopRepl

Version 11

tobi — Wed, 15 Oct 2008 15:31:45 +0200

Changed tags to shell, introspection, Tobi, REPL

187	* <s>Eat those nasty java.lang.Nullpointer exceptions (could be something with entering Java class context)</s> Fixed by preventing HopRepl from entering scopes with undefined constructor property.

Version 10

tobi — Mon, 18 Feb 2008 11:26:13 +0100

17	<em>Update:</em> I added the file <code>patch-for-emacs-integration.diff</code> which Massimiliano sent to me; he "added a few bits, namely set/get/push/popenv and the multiline input mode, needed for EmacsEmacs integration." Maybe this helps other Emacs users, too.
18	integration." Maybe this helps other Emacs users, too.

Version 9

tobi — Mon, 18 Feb 2008 11:25:53 +0100

17	<em>Update:</em> I added the file <code>patch-for-emacs-integration.diff</code> which Massimiliano sent to me; he "added a few bits, namely set/get/push/popenv and the multiline input mode, needed for Emacs
18	integration." Maybe this helps other Emacs users, too.
19

Version 8

tobi — Sat, 19 Jan 2008 12:53:53 +0100

172	Please note that the e-mail address is not changed in the database, yet. To achieve this one could has to add a <code>res.commit()</code> at this point. After invalidating the application – which of course could can be done in HopRepl as well by invoking <code>app.clearCache()</code> – the new value will also be displayed when its property is requestedstill persistent:
178	REPL> dataRoot.creator.email
179	somebody@somewhere.com

Version 7

tobi — Sat, 19 Jan 2008 12:47:36 +0100

172	Please note that the e-mail address is not changed in the database, yet. To achieve this one could add a <code>res.commit()</code> at this point. After invalidating the application – which of course could be done in HopRepl as well by invoking <code>app.clearCache()</code> – the new value will also be displayed when its property is requested.:
174	REPL> res.commit()
175	REPL> repl.back(); repl.back() // Back to the application's context
176	[Application antville]
177	REPL> clearCache()
178

Version 6

tobi — Sat, 19 Jan 2008 12:40:12 +0100

172	Unfortunately, this version of HopRepl being absolutely Please note that the e-mail address is not changed in alpha stage cannot change the database value of propertiesdatabase, yet. At least I currently did not succeed in doing soTo achieve this one could add a <code>res.commit()</code> I cannot even predict if at this will point. After invalidating the application – which of course could be possible done in that manner.HopRepl as well by invoking <code>app.clearCache(.)?</code> – the new value will also be displayed when its property is requested.
174	However,That's it so far. maybe Maybe this first attempt will grow and if anyone is interested in picking up the pieces, please contact me via the helma-dev mailing list.
179	* <s>Allow modifications of properties to trickle down to the database</s> Works with <code>res.commit()</code>

Version 5

tobi — Thu, 17 Jan 2008 16:27:42 +0100

169	REPL> email = "somebody@somewhere.com"

Version 4

tobi — Thu, 17 Jan 2008 16:21:18 +0100

1	=== Introduction
2
178	* Allow modifications of properties to trickle down to the database

Version 3

tobi — Thu, 17 Jan 2008 16:17:50 +0100

5	<small>Note: Chris Langreiter was here years ago already when he published <a href="http://www.langreiter.com/space/HopShell">HopShell</a>., I don't know what happened to it right nowa REPL written in Rebol.</small>

Version 2

tobi — Thu, 17 Jan 2008 16:15:06 +0100

Changed tags to Tobi, REPL, shell, introspection

3	HopRepl actually is similar to HopShell <a href="https://dev.helma.org/trac/helma/browser/apps/helmaTools/trunk/Global/helma.shell.js">Helma Shell</a> with the tiny difference that it does not run in a browser window but in a terminal environment (aka command line).
5	<small>Note: Chris Langreiter was here years ago already when he published <a href="http://www.langreiter.com/space/HopShell">HopShell</a>. I don't know what happened to it right now.</small>
6
16	=== Installation and setupAnd Setup
18	First, move the two files attached to this wiki as repl.zip and repl.jar into you your application directory. I recommend the manage application because it already provides some interesting objects to explore.
171	However, maybe this first attempt will grow and if anyone is interested in picking up the pieces, please contact me via the helma-dev mailing list. // tobi
172
173	=== To Do
174
175	* Eat those nasty java.lang.Nullpointer exceptions (could be something with entering Java class context)
176
177	// tobi

Version 1

tobi — Thu, 17 Jan 2008 15:00:48 +0100

Set tags to shell, introspection, Tobi, REPL

1	Inspired by Massimiliano Mirra's <a href="http://hyperstruct.net/projects/mozrepl">MozRepl</a> project I quickly coded a similar tool, for now dubbed HopRepl.
3	HopRepl actually is similar to HopShell with the tiny difference that it does not run in a browser window but in a terminal environment (aka command line).
4
5	The four letters <a href="http://en.wikipedia.org/wiki/REPL">REPL</a> actually are in fact used synonymously for a shell.
6
7	Thus, you can enter simple commands to inspect and manipulate Helma space. And commands are of course JavaScript statements!
8
9	This is an alpha version, ie. you will get excepctions, stuck and not always what you expected.
10
11	Thanks to Robert and Hannes for their help; it wouldn't be even alpha without them.
12
13	Here's what you can do with it:
14
15	=== Installation and setup
16
17	First, move the two files attached to this wiki as repl.zip and repl.jar into you application directory. I recommend the manage application because it already provides some interesting objects to explore.
18
19	<% this.attachments %>
20
21	To be sure that the HopRepl code is really compiled into the application a Helma restart won't hurt.
22
23	Now you can start the HopRepl server by navigating to the "repl" action in your browser. In my case the location is http://localhost:8080/manage/repl
24
25	There you will see one simple line saying "HopREPL server (stopped)" followed by two links "Start" and "Restart".
26
27	Click on the "Start" link and your HopRepl should be started. Simultaneously, the link will change to "Stop" and the port number will be displayed in brackets.
28
29	(If not you might check if anything else is running behind that port on your computer already. Use the application property replPort to change the port number.)
30
31	=== Using HopRepl
32
33	Let's check if you can connect from the command line shell to the HopRepl server by entering
34
35	telnet localhost 1234
36
37	(Be sure to use the desired port number if you should have changed it in the previous step.)
38
39	If everyhing goes well HopRepl should welcome you with a short message and the REPL prompt:
40
41	Hello! This is HopRepl Alpha (c) 2008 Tobi Schäfer
42	REPL>
43
44	After the prompt you can enter any JavaScript statement you like. It will be (R)ead, (E)valuated and the result will be (P)rinted in your terminal. Finally, the (L)oop starts again with your next input. That's the generic principle behind REPL.
45
46	REPL> new Date
47	Thu Jan 17 2008 12:21:57 GMT+0100 (CET)
48	REPL> Math
49	[object Math]
50	REPL> this
51	[object GlobalObject]
52
53	There is one special object added to the JavaScript as defined by Rhino and Helma. It is called repl and acts as a helper object providing methods to make navigating and exploring the namespace more convenient.
54
55	REPL> repl
56	HopREPL server (port 1234)
57
58	To get a clue where in Helma space you are right now you can use the whereAmI() method:
59
60	REPL> repl.whereAmI()
61	[object GlobalObject]
62
63	The look() method prints a list of all available properties and methods in the current context:
64
65	REPL> repl.look()
66	this.Repl = [function]
67	this.Server = [function]
68	this.Thread = [function]
69	this.Xml = {class helma.scripting.rhino.extensions.XmlObject}
70	this.app = {class helma.framework.core.ApplicationBean}
71	this.appStat = [function]
72	this.checkAddress = [function]
73	this.checkAuth = [function]
74	this.createAddressFilter = [function]
75	...
76	this.req = {class helma.framework.RequestBean}
77	this.res = {class helma.framework.ResponseBean}
78	this.root = {class helma.main.Server}
79	this.scheduler = [function]
80	this.session = {class helma.framework.core.SessionBean}
81	this.skin_macro = [function]
82	this.sortByName = [function]
83	this.sortProps = [function]
84
85	For convenience you don't have to always type in "this" to access a property or a method. HopRepl provides all available properties of the current context as global variables:
86
87	REPL> res
88	[Response]
89	REPL> session
90	[Anonymous Session]
91	REPL> skin_macro
92	function skin_macro(par) {
93	if (par && par.name) {
94	renderSkin(par.name);
95	}
96	}
97
98	The enter() method changes the context to another object:
99
100	REPL> repl.enter(root)
101	helma.main.Server@d03ed2
102	REPL> repl.look()
103	this.application = undefined
104	this.applications = {class [Ljava.lang.Object;}
105	this.appsHome = {class java.io.File}
106	this.appsProperties = undefined
107	this.checkAppManager = [function]
108	this.class = {class java.lang.Class}
109	this.dbHome = {class java.io.File}
110	...
111	REPL> repl.enter(checkAppManager)
112	function checkAppManager() {/*
113	void checkAppManager(int)
114	*/}
115
116	To get back to the previous context the back() method is at hand:
117
118	REPL> repl.back()
119	helma.main.Server@d03ed2
120
121	And the home() method brings you even further back, straight up to the top-level context:
122
123	REPL> repl.home()
124	[object GlobalObject]
125
126	If you should have enough of tinkering with HopRepl the quit() method closes the connection to the server:
127
128	REPL> repl.quit()
129	Connection closed by foreign host.
130
131	=== Getting Nifty
132
133	Of course you can also call methods, not only enter their contextes. Here's a more elaborated example of using HopRepl to stop an application:
134
135	REPL> repl.home()
136	[object GlobalObject]
137	REPL> repl.enter(root)
138	helma.main.Server@d03ed2
139	REPL> repl.enter(getApplication("test"))
140	[Application test]
141	REPL> isRunning()
142	true
143	REPL> stop()
144	REPL> isRunning()
145	false
146
147	Further manipulation is possible, too. Let's change a HopObject's property:
148
149	REPL> repl.home()
150	[object GlobalObject]
151	REPL>> repl.enter(root)
152	helma.main.Server@d03ed2
153	REPL> repl.enter(getApplication("antville"))
154	[Application antville]
155	REPL> repl.enter(dataRoot)
156	HopObject Site 14
157	REPL> repl.enter(creator)
158	HopObject p3k
159	REPL> repl.look()
160	this.comments = [object]
161	this.created = [object]
162	this.email = nobody@nowhere.com
163	this.files = [object]
164	...
165	REPL> email = somebody@somewhere.com
166	somebody@somewhere.com
167
168	Unfortunately, this version of HopRepl being absolutely in alpha stage cannot change the database value of properties. At least I currently did not succeed in doing so. I cannot even predict if this will be possible in that manner...?
169
170	However, maybe this first attempt will grow and if anyone is interested in picking up the pieces, please contact me via the helma-dev mailing list. // tobi