X-Authentication-Warning: delorie.com: mail set sender to geda-user-bounces using -f X-Recipient: geda-user AT delorie DOT com X-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sbcglobal.net; s=s2048; t=1437260226; bh=dxi1NMfkfjLtvaSLHkrnF72WKGeA8J1dYvlSeBLd1ac=; h=Date:From:To:Subject:References:In-Reply-To:From:Subject; b=hd8ZIBA29lFWq1ZRu6f2o6KrZ2BTSRS8eDY3nNR3lo3Bx2t3LtiY/j2/A38b6MXD19gorCC3GjyFtPayRf974eHFoYNOedgW9F+zt0krSsc3VgZrPyKrcLlc4/thKPHlOBpuSXvj4ysqGUwgvIF80LtuytNn6TcIJD6DJvezs6V6QXFKXnJmqSbPqD+pisT1r598WV4xurKxTMQwxvgL0hbPhpM0Kc16MRQPQrZ74wbxdMtDXJI0Xzb6N/FCcxnuIvdBxlah6hlKabtSBq+EoTYMwSQmOY+OxUp0tlGV/IoBanS2fWQv192dGity1utvRok42Yw0ZZxCt+uY8pHoVw== X-Yahoo-Newman-Id: 779325 DOT 26902 DOT bm AT smtp111 DOT sbc DOT mail DOT ne1 DOT yahoo DOT com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: bboEy0wVM1mRRGNL6MCDY.6zD3toAwBlIbBHW4cbc2Xzbnw xS_DnxxS9qbDUZLdb_4AmERWQTeKrAI2W3Tq4tYO7VutoAkidNjtgNZTwQSH pz8NCwsNHYy_VM3EpBo5_a8xjvpNG0iaezq2p2MeJOsqUK07FpsLY3t__ce1 KnAY3hS3ad9GN_dHWfIBFoeYfH.zsERM58dY2LyCRfWPXPIQ0_9tEFbaGx6Q a_fLV6ExvmxSM1sFORDXHSnc70ZLw8CGRG0HgdzENyNSebqCXaPeJC01h_gv NEvLzcTF_v_k.0BZ2QHNoi2Dr9VlEjxJx7kGkgwKVtLrNIdwniclZI_cUIKD TrfitSvH_lQ7CLx8wsl9kfpiDdK52NjDMIvAsFH3x333cV0lAdnD44KcS1mx zcPvCA267k6Qc3bV5oVzzYZgjRAXDVKadInULXw2lwRp84DVROC5_.wVt96V 6f4as04lQl36rn4liZUxYbY9cOUzYNTZ7y39Y7ZtMp01QpoRyTJzJ8hvecuh Elt1Y0R_rIqkhVPnUWbWN7LfEDiC8Xkc18gLmp6OngsdmYeUTQQM- X-Yahoo-SMTP: xaem6kSswBCHwCBMr0jlCBIQdXYGmRxsm8OX6ACyP7Ho9Sk- Message-ID: <55AAD92F.6090406@sbcglobal.net> Date: Sat, 18 Jul 2015 15:54:39 -0700 From: "Girvin R. Herr (gherr375 AT sbcglobal DOT net) [via geda-user AT delorie DOT com]" User-Agent: Mozilla/5.0 (X11; Linux i686; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: geda-user AT delorie DOT com Subject: Re: [geda-user] Difference between attached and detached attributes References: <55A813B5 DOT 4040609 AT sbcglobal DOT net> In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Reply-To: geda-user AT delorie DOT com On 07/18/2015 03:09 PM, Roland Lutz wrote: > On Thu, 16 Jul 2015, Girvin R. Herr (gherr375 AT sbcglobal DOT net) [via > geda-user AT delorie DOT com] wrote: >> I have been doing some symbol work in gschem and I got confused again >> about attached attributes vs detached attributes. The manuals do not >> go into detail about usage. Hint, hint. Can someone tell me what is >> the difference between them and where I should apply one vs the other? > > An attribute is a specially formatted text object which can be > attached to a component, net, bus, or pin, or not be attached at all. > > An attribute which is not attached to an object is called a "floating" or > "toplevel" attribute. Floating attributes are used for two purposes: > in a > symbol, they contain default attribute values. In a schematic, they > contain information global to that schematic page; for example, the VHDL > backend searches for a toplevel "module-name" attribute in the schematic, > and John Doty's spice-noqsi backend searches for "spice-prolog" and > "spice-epilog". > > An attribute which is attached to a component overrides the value from > the > symbol's floating attribute. (There are some exceptions to this like the > "graphical=1" attribute which can't be properly unset by attaching an > attribute to the component.) You can delete an inherited attribute by > attaching an attribute with the value "unknown" to the component. > > You can't attach an attribute to a specific pin of a component's > symbol, so you can't override pin attributes when you instantiate a > symbol in a schematic. There is a special slotting mechanism, though, > which allows you to select one of a set of pre-defined pin numbering > schemes. > > It is important to understand that the attributes inherited from the > symbol (both floating and attached to a pin) live in the symbol file, > whereas the attributes attached to the component live in the > instantiating > schematic file. You don't have a way to change the symbol from the > instantiating schematic; the way to change inherited attributes is to > attach an attribute with the same name and another value to the > component. > (You could obviously change the symbol by embedding it and hacking the > schematic file, but AFAIK, there is no way to do this in gschem.) > > When creating a component, some floating attributes from the symbol are > usually copied to the schematic and automatically attached to the symbol, > hiding the inherited attributes. This is called "attribute promotion". > The default set of promoted attributes is: footprint, device, value, > model-name, and symversion. > > The menu items "Attributes/Attach" and "Attributes/Detach" are used to > attach floating attributes to components, nets, buses, and pins, and > to convert attached attributes back to floating attributes. You don't > need these for normal gschem usage. (If you still want to try them, > take extra care not to accidentally lose invisible attributes. You > can type "e n" to make invisible text temporarily visible.) > > Roland > > Roland, Thank you. This is a good explanation of attributes and their uses. This explanation should go into the attributes document for others to see. Thanks again. Girvin Herr