Matthew R. Wilson
b6fa48f37f
This is a relatively big new feature, which introduces small breaking changes to the API: * NegotiateTelnet() now returns (DevInfo, error) instead of just error. The function signature for the Tx type now has one additional DevInfo parameter. * RunTransactions() requires one additional parameter, the DevInfo (which is allowed to be nil). Otherwise, existing behavior continues to work as-is and everything still defaults to operating on the default 24x80 terminal size. See example5 for a larger-terminal-aware application. Pending some time to make sure no new bugs cropped up in this release and that the alternate screen size support works in the wild, I anticipate this will become the v1.0.0 release of go3270.
70 lines
2.3 KiB
Go
70 lines
2.3 KiB
Go
// This file is part of https://github.com/racingmars/go3270/
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// Copyright 2025 by Matthew R. Wilson, licensed under the MIT license. See
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// LICENSE in the project root for license information.
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// This example demonstrates using the RunTransactions() approach to
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// structuring a go3270 application.
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// This file contains the help transaction generator.
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package main
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import (
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"net"
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"github.com/racingmars/go3270"
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)
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var helpScreen = go3270.Screen{
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{Row: 0, Col: 45, Intense: true, Content: "Online Help"},
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{Row: 2, Col: 0,
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Content: "This help screen is an example of a transaction that"},
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{Row: 3, Col: 0,
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Content: "can be used as the next transaction from many other transactions"},
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{Row: 4, Col: 0, Content: "and returns to the transaction that called it."},
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{Row: 6, Col: 0, Content: "Press"},
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{Row: 6, Col: 6, Content: "PF3", Color: go3270.White, Intense: true},
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{Row: 6, Col: 10,
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Content: "to return to the transaction from which you came."},
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// Error message
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{Row: 21, Col: 0, Name: "errormsg", Color: go3270.Red, Intense: true},
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// Key legend
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{Row: 23, Col: 1, Content: "F3=Exit"},
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}
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// The help transaction is an example of returning a closure over a parameter,
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// in this case the desired next transaction. This allows us to use the same
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// transaction from multiple other transactions and return to the requested
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// transaction when the user leaves the help transaction.
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//
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// Any data passed to help will be passed back to the transaction it returns
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// to.
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//
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// The help transaction has no need for any global or session state, so this
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// generator function for it is a stand-alone function and not a method on the
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// session.
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func help(returnTransaction go3270.Tx) go3270.Tx {
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return func(conn net.Conn, _ go3270.DevInfo, data any) (
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go3270.Tx, any, error) {
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_, err := go3270.HandleScreen(
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helpScreen, // the screen to display
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nil, // (no) rules to enforce
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nil, // pre-populated values in fields
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[]go3270.AID{go3270.AIDPF3}, // keys we accept
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nil,
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"errormsg", // name of field to put error messages in
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23, 79, // cursor coordinates
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conn)
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if err != nil {
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return nil, nil, err
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}
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// Any accepted key returns to the requested returnTransaction
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return returnTransaction, data, nil
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}
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}
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